Fatherly Love or Grooming ?
In Diabolik Lovers, many relationships are built upon possession, dependency, and emotions distorted far beyond ordinary standards. Unsurprisingly, the relationship between Yui and her adoptive father, Seiji, is no exception.
Unlike the other male characters, Seiji did not enter Yui’s life as a potential romantic partner. He entered it as her father.
Seiji raised Yui from infancy.
He was the only family she knew throughout her childhood.
For a long time, many fans viewed Seiji’s feelings for Yui as purely paternal. However, as the series progressed—especially with the release of More Blood, Dark Fate, and Lost Eden—that interpretation began to show cracks.
What the canon presents suggests that Seiji’s feelings extend beyond the responsibilities of a father.
They contain genuine affection, but also control.
Protection, but also possession.
They begin as familial love, yet end somewhere that the simple label of “father and daughter” can no longer fully explain.
After Richter took Cordelia’s heart and implanted it into the body of an abandoned infant, that child was entrusted to Seiji’s care.
That child would later become Yui.
To Seiji, Yui was not his biological daughter. Yet that never mattered.
In a diary entry shown in the anime (Episode 1 Ss 1), he wrote:
"Yui brings me happiness. The fact that she is not my biological daughter does not matter. Every day, I give thanks for this precious gift."
A short sentence, yet it reveals a great deal.
Yui was never merely an adopted child.
She was his happiness (Ruki MB Epilogue).
The most precious thing in his life.
At first glance, this can easily be interpreted as a father’s love. The issue is that, over time, Yui gradually became the emotional center of Seiji’s entire existence.
Built his life around her.
And, perhaps unknowingly, placed the entire meaning of his life upon the existence of a single person.
That is a dangerous foundation.
Because when one person becomes someone else’s entire world, love can easily transform into dependency.
🔑 The Way He Raised Her 🔑
Seiji did not simply raise Yui—he constructed an idealized image of her.
One detail that is often overlooked is the lens through which he viewed her.
“Pure like the Virgin Maria” is arguably the standard by which Seiji raised Yui from childhood.
This is not how an ordinary father typically describes his daughter.
It suggests that, in Seiji’s eyes, Yui was more than just a child.
An ideal he wished to preserve.
And this is the key issue.
When we love a person, we accept that they will change.
When we love an idealized image, however, we often cannot tolerate any change that threatens that image.
But he also loved the version of Yui he had created in his mind.
Belonging neither to the world of vampires nor to anyone else.
Like the perfect devout lamb, Yui became the ideal that Seiji wanted her to remain.
The tragedy begins when Yui matures.
Once she becomes entangled in the world of vampires, everything begins to change.
What is important to note is that Yui never stopped loving her father.
Never forgot him—she constantly worried about his safety even when she herself was suffering hard.
She never intentionally abandoned him.
What changed was that she grew up.
She developed her own choices.
And that was precisely what Seiji could not accept.
After returning to Japan, Seiji reunites with Yui in Azusa’s and Kanato’s routes in More Blood. By that point, he barely sees her as his daughter anymore.
Merely sensing the scent of vampires on her, he concludes that she has been corrupted. He loses control, draws a gun, and is prepared to kill her as though she were a monster.
In Dark Fate, he follows Ruki’s orders to target Kou and shows no mercy toward Yui when the two attempt to escape together, even pointing a gun at her.
In Lost Eden - Vampire End (Kino), Seiji strangles Yui in an attempt to kill her. In the same route’s Manservant End, he and the Church burn his adopted daughter alive.
At first glance, it appears to stem from the convictions of a vampire hunter.
But the deeper issue lies elsewhere.
A father who loves his daughter unconditionally would try to understand the reasons behind her change.
Seiji instead chooses denial and attempts to kill her because he believes she has become "defiled."
Even Kou points this out:
(Dark Fate – Kou Ecstasy Prologue)
Seiji cannot accept who Yui has become.
He can only accept the version of Yui preserved in his memories.
The version that belonged to his world.
When Yui ceases to be that girl, Seiji experiences it as a loss.
Her growth and independence represent an escape from his control.
The bird he once nurtured inside a cage can now spread its wings and fly away without relying on him.
To Seiji, that loss of control feels dangerous.
Yui never truly betrayed her father.
Theoretically, that is true.
Yet in terms of power dynamics, she did.
The Sakamaki brothers were always established as predators, while Yui was the prey. That boundary was clear from the beginning.
With Seiji, the boundary was trust.
Yui entered the vampire world as a dutiful daughter seeking guidance from her father.
When Seiji points a gun at her, attempts to kill her, or later seeks to marry her, he destroys the very foundation of safety and trust he spent seventeen years building.
It is a profound psychological betrayal—a classic abuse of trust.
✒️ Why Do I Believe Seiji Groomed Yui?
This is likely the most controversial part of the discussion.
To be clear, there is no scene in the original work where Seiji explicitly says:
"I raised Yui so I could marry her one day."
No such direct evidence exists.
However, what leads many people to associate this relationship with grooming is not Seiji’s original intention.
It is the structure of the relationship itself.
First, we should briefly define grooming.
Grooming is a psychological and criminological term describing a process in which someone builds trust, dependency, or influence over another person—often a child or someone vulnerable—in order to manipulate, control, or exploit them later.
Grooming does not necessarily begin with abuse.
On the contrary, it often begins with actions that appear caring, protective, or loving.
Common characteristics include:
Building deep trust and attachment.
Becoming the most important person in the victim’s life.
Encouraging emotional dependency.
Isolating them from other sources of support.
Creating the belief that "only I truly understand and love you."
Maintaining a significant power imbalance.
Gradually normalizing boundaries that would once have been unacceptable.
An adult befriends a child, constantly buys gifts, listens to all their worries, and becomes the center of their emotional world. Years later, that person turns the relationship romantic or exploits the dependency for personal gain.
That is a textbook example of grooming.
Seiji raised Yui from the moment she was an infant.
He taught her how to view the world.
He determined her environment.
He was the most powerful authority figure in her life.
Yui grew up inside a world created by Seiji.
To her, he was simultaneously:
Throughout Season 1 and Haunted Dark Bridal, Yui consistently views Seiji as an admirable yet strict father.
The way she speaks of him throughout the early story demonstrates just how profound his influence was. Even after being sent into what she experiences as a living nightmare, she never blames him.
Instead, she continues to trust him completely.
This suggests that Yui’s worldview was anchored almost entirely around Seiji.
Furthermore, small details such as Yui’s poor familiarity with mobile phones (Lost Eden – Kino) or her lack of knowledge about idols (More Blood – Kou/Subaru), despite idols being a part of Japanese culture, subtly imply a disconnect from the outside world.
Though she is a teenager, she has little exposure to phones, television, or broader society.
Her understanding of life comes almost entirely through her father’s teachings. As a result, she often appears isolated from other girls her age.
When a child grows up in such isolation, the role of "father" can become a mechanism through which one person gains extraordinary influence over the child’s worldview.
In psychology, raising a child while limiting exposure to alternative perspectives can function as emotional isolation.
When Yui knows only "her father’s world," her morals, beliefs, and understanding of happiness become deeply intertwined with Seiji himself.
This mirrors one of the fundamental elements often discussed in grooming dynamics: the gradual establishment of a single authority figure as the primary reference point for the victim’s thoughts and values.
The power imbalance within the relationship is undeniable.
Yui is the dependent child.
From this perspective, one could argue that Seiji successfully shaped Yui’s worldview into one centered almost entirely around him.
Whether intentional or not, that imbalance becomes deeply significant when later developments are taken into account.
Most importantly, when Yui grows up, Seiji does not truly accept her independence.
Rejects the people she loves.
Rejects the path she wishes to follow.
He repeatedly attempts to decide for her.
To pull her back into the life he believes is right.
And this is precisely why many readers see echoes of grooming and unhealthy emotional dependency within their relationship.
❗The Game Changes Everything❗
If earlier installments still allowed room for multiple interpretations, Lost Eden changes the landscape entirely.
Especially in Subaru’s Brute End.
In that ending, Seiji kills Subaru and marries Yui. Beside, He himself asserted that he had always "loved" Yui. He even wanted to become part of Yui's "family" in the sense of a life partner? This means that this distorted feeling had been present for a long time.
That fact alone makes it difficult to continue viewing their relationship as purely paternal.
These are not two adults who met later in life.
This is the man who raised her from infancy.
The man she called Father.
The man who occupied the parental role throughout her entire childhood.
And in the end, he becomes her husband.
What makes the situation even more controversial is Seiji’s wedding dialogue:
These are not the words of a father.
Nor the words of someone who has learned to let go.
They are the words of someone who has finally achieved what he has long desired.
"Now you can truly become mine."
The language is intensely possessive.
It is not the language of protection.
It is the language of ownership.
A declaration that a long-held desire has finally become reality.
He does not speak like a father welcoming his daughter home.
He speaks like someone reaping the reward of a long-term investment.
Placed alongside the full history of their relationship, it becomes increasingly difficult to interpret Seiji’s feelings as merely paternal.
Why did Seiji choose marriage?
The answer can be summarized in two words: Binding ownership.
Rather than simply imprisoning Yui, marriage offers a more socially and emotionally secure way to keep her as his own.
Marriage is not the act of a father.
It is the act of someone who has waited years to claim what he believes belongs to him.
In Seiji’s mind, this distorted choice fills the void of his obsession by creating the reassurance that Yui finally belongs to him.
That marriage stands as the clearest evidence that Seiji failed as a father—at least in the moral sense—and succeeded as a possessor.
No matter how one interprets it, Seiji’s decision remains one of the most difficult aspects of his character for me, and for much of the fandom, to accept.
Previously, Seiji had also kissed Yui's hand and said "I love you" in a very questionable way in Subaru's route.
Is this a way of affirming his love for his adopted daughter in that particular way from the start?
⁉️ Love, Obsession, or Ownership? ⁉️
This may be the most important question of all.
It would be difficult to argue that Seiji does not love Yui.
- He spent years caring for her.
- He found happiness in her.
- He suffered when he lost her.
- He could not let her go.
There is clearly love here. But is it healthy love? Probably not.
Healthy love requires respect for another person’s autonomy.
Seiji repeatedly denies Yui that autonomy.
He wants to choose for her.
To save her according to his own standards.
To keep her by his side regardless of her wishes.
In other words, Seiji loves Yui.
But he loves her in a way that cannot let go.
Cannot accept that she belongs to a world beyond his control.
And that is precisely why his love gradually transforms into obsession.
Seiji Komori is one of the most tragic characters in Diabolik Lovers because he did not begin as a villain.
But over time, that love became distorted by extreme faith, fear of loss, and an overwhelming need for control.
He could not accept Yui becoming an independent person.
He could not accept her right to choose her own path.
Nor could he accept her desire to define herself rather than follow the life he had envisioned for her.
And so, instead of letting her live her own life, he tried to keep her trapped within the world he had built around her since childhood.
For that reason, calling Seiji’s feelings simply paternal is far too simplistic.
Calling them ordinary romantic love is equally inaccurate.
Perhaps the most fitting description is a form of affection that began as sincere love, but gradually mutated into obsession, possessiveness, and a relationship that shares many characteristics people associate with grooming—especially when his ultimate desire was to marry the very daughter he had raised since infancy.
It is this mixture of love, salvation, control, and ownership that makes the relationship between Seiji and Yui one of the darkest and most complex dynamics in the entire series.
If Seiji’s love for Yui was truly nothing more than pure fatherly affection, then why did he become so extreme in his desire to possess her?
Why would a father choose to marry the daughter he raised?
And why would a father be willing to kill his own child simply because the ideal image he had created for her was shattered?
This is an article written from a personal perspective. It is not a fact; please do not misunderstand.
