i need help finding a manga!

I remember it was either tagged shounen ai or yaoi and I've been looking through the tags and I still can't find it after weeks so... Anyways it's about this guy who has a reunion with his art club and he starts reminiscing about his old friend whose art he loves. He hasn't seen him for years and he wasn't at the reunion either. When MC brings him up at the reunion it gets awkward and some people act suspicious. Then on the news, he finds out his friend is dead and his body was hidden in the art club walls. Obviously, he's shocked and then gets sent to the past to HS and is determined to save his friend.