Spoiler for do i need tags for this?:
1) Yakumo gave the chocolates to Iori. Iori was probably in cahoots with Akira to destroy Hanai's sanity (or love for women), so he batted it into Hanai's room.
2) Harima didn't even see Eri give him chocolates, thanks to Akira.
My take on this is that Akira has a thing for shonen-ai and is trying to hook up Hanai and Harima. She's obviously been trying to sabotage the Valentine's Day affair and who knows what other incidents she may have been behind.
Don't believe what the pictures tell you! It's a lie!
It's all a lie to cover up the real story of love lost gone wrong and the secret plans of a yaoi fangirl! Lies!!!