if mei love misato why he using (satoshi's nickname) this is very cruel.

I think it's because he's been so engrossed with the name Sato, that it has ended up taking a whole new meaning as "the person I'm in love with". He's so confused that at one point he's not even sure which Sato is the one he's referring to. I really dislike it when someone over-analyzes things to make metaphors and to make them look "deep", but I think that the twisted parts of this story have been placed neatly. Good work, really and really fitting with Madarame Hiro's art :D