Mirai Nikki OVA

A middle school student named Yukiteru Amano struggles with social interactions and often records his observations in a phone diary, viewing himself as an outsider. Feeling isolated, he imagines a friend named Deus Ex Machina, a being associated with time and space. Moved by Yukiteru's loneliness, Deus grants him a power that allows his diary to document future events. Yukiteru is then drawn into a game where the winner will inherit Deus's role. This brief OVA was included with the limited edition of the manga's eleventh volume.