The Diary of a Sentimental Killer

Akito works for the Japanese army as a 名誉ある戦士 (Honorable Warrior). In a society where some people are born with special powers - ranked from white to red, with red being the strongest - he's the only one who's classified as black. After being told to wipe out an entire country with his abilities, he decides to take a break and retire for a while. This diary follows his life during that time, exploring his inner struggles along with his growing relationship with a free-spirited schoolgirl.