Your just an average dude in a high school your sister azusa doesn't want to be around you any more, same as yuzuki she is now using her chest as a... weapon?, and kirari who became a delinquent she changed from a nice timid girl to... yeah, and there's ryouma-san who they all love... but they forgot you..

you forgot something at school so you went to ger it and you saw.. Shimotsuki-san the heroine of thus story, as you thought, she was just sleeping there.. so you went to wake her up, but she jumped on you

'Shimotsuki-san:' got you! she starts to feel your hand I knew I could speak to you with out getting nervous!

[BTW Shimotsuki-san is friends with ryouma-san]