I Was The Only One To Regress

Ottilie Von Prunella, the crown prince of the Kingdom of Prunella, at twenty-nine years old died one month before his thirtieth birthday admist a war with his best friend at his side. When he next woke he found himself nearly two decades in the past as his twelve year old self. Given this second chance he decided he will gain the upper hand on the inevitable war by summoning heroes from another world and saving his best friend from his traumatizing childhood while he's at it, unknowingly creating many misunderstandings along the way.