Look, my interpretation is this: Mikey is a vulnerable person. He wants Takemichi to control him, scold him, and keep him in check from any foolishness he might commit, just like Shinichiro used to do.
But it’s clear that, even though he compares them, he doesn’t categorize them as equals in his life or see them in the same way. He always says to take care of him, but he never specifically says to do it like a brother.
And it might sound far-fetched, but just think about it: there’s not just one scene where he says to take care of him but doesn’t specify to do it like a brother—there are TWO scenes. That’s deliberate on Wakui’s part.
He was drawing the story with a deadline, so he had to carefully plan the dialogues.
Besides, Mikey never lacked brothers. He has all of Toman, who are practically brothers, a family. And let’s not even talk about Draken, who literally acts like his babysitter. Draken also takes care of him.
So, the care he wants from Takemichi is different—it’s much deeper and more complex than it seems. Mikey sees something in Takemichi; he inspires trust in him, and Takemichi has a certain power over him to calm his dark impulses. He’s not asking Takemichi to take care of him like a kid, but to be with him because he feels Takemichi is the only one who can help him with his curse. Because Takemichi is the only person who can keep his sanity in check. That same power over him was something Shinichiro had.
It’s not that he needs a brother; he needs that comfort and security from the two people he loves.
And this becomes even more obvious in Manila. Thirteen years had passed since the Takemichi from the past “left him,” so to speak, and yet Mikey still remembered him, loved him, and needed to see him. I mean, are you telling me that someone spent thirteen years obsessed with someone just because they reminded him of his little brother, to the point of killing his childhood best friends? What did Takemichi have that the others didn’t?
Easy: Mikey wasn’t looking for Takemichi because he needed a brother. He was looking for him because Takemichi was someone who helped him feel better and provided him with warmth. That’s why, as he was losing his life and his senses were fading, he could feel warmth when he touched Takemichi’s hands.
So, those two panels don’t mean that he wants Takemichi to take care of him like a brother or that he considered him one. He mentions Shinichiro because he was his first safe haven, the only one who knew about his curse and could control him. That’s why he also tells Takemichi, so that he knows and can take care of him too. And even though he compared them at first, he never gave any indication that he saw them as equals. Shinichiro is his brother, and Takemichi is just a friend.
Mikey hates his dark impulses and desperately wants someone to protect him from his curse, just like Shinichiro did. That’s the meaning behind those two panels.
Of course, he misses Shinichiro and it hurts him. At first, Mikey approached Takemichi because he reminded him of his brother’s values and determination, but he has never seen Takemichi as a replacement for Shinichiro. He loves Takemichi simply for who he is, because he has observed him, lived through things with him, and knows him.