If you think about it Yashiro and baby Tsukasa have many things similar….
When Hanako describes her.. it seemed to me at first he was saying things he started to notice as he slowly started to fall for her HEAR ME OUT I still think Hanako did caught romantic feelings for Nene for sure but what if the feels started up w him feeling safe and comfort w her because she gave him the same comfort and safety as his little brother, which parallels w Tsukasa and Hanako, Tsukasa sacrifice himself for his brother and Hanako will do anything for Yashiro.
Before the twins were so close but it seems since amane got sick they got distant maybe?
And all of this makes me think about this panel, Hanako was very upset knowing how bad he hurt Yashiro feelings and a part of that besides him actually gaining feelings for her could be because he knew he hurt his brothers well?