Shikamaru accepts that kiss as easily as if under a spell. The moment Souji draws in, his defenses fall away and he finds himself kissing Souji - kissing him without any desire to stop. His hand rises, and he must have meant to put it on Souji's chest and push him away, but instead his palm caresses Souji's cheek.

Whatever had possessed him to want to hurt Souji is gone now. But he can't think of any way to make it better. He only feels that he owes this to Souji... and if he's honest with himself, he craves Souji's attention and affection just as much.