Ore wa Shiranai Uchi ni Gakkouichi no Bishoujo o Kudoiteita Rashii ~Baito-saki no Soudan Aite ni Ore no Omoibito no Hanashi o Suru to Kanojo wa Naze …

[colorlesseatstomboys]

So... was she his friend's past love in middle school? The reason he turned frivolous? I guess you need drama to keep the story going, but I'm asking for moderation here, please.
BTW, the way she softened up just by looking at him was cute.

Exactly what I thought.
This also connects why he knows exactly that she hates his "type" of guys.