In fact, Tsukasa just got tired of feeling sad, of feeling rejected, of feeling frustrated with other people's actions and judgments. He got tired, as if he had no more tears to dry, as if he knew it would be no use, because no one would care.

He didn't cry even before he discovered the entity, and he was suffering, seeing that his brother's death was near.

Tsukasa is not a monster, he never was. He doesn't cry because he believes it's not worth it. He just accepts how things are and doesn't regret it.

Despite this, he almost gave in a few times.

Don't be fooled, Tsukasa has feelings, he feels pain, he want to receive love, and this is reflected in his actions when Yashiro hugged him without fear.

When Hanako saved him for the first time.

Tsukasa is someone who is surprised to be loved. He is used to being despised and treated like a "monster" by everyone, but in the end he is still just a little boy who sacrificed himself to save the brother he believed hated him.

He saw the entity as a refuge, a way to fulfill his wish of saving the one he loved most, and having someone who would listen to him.

Hanako shows the pain he feels through his actions, but he doesn't say what he really feels, and that is why Tsukasa suffers.

Because Hanako is not honest.