Yukiteru's father who is divorced with Yukiteru's mother due to a debt amounting to three million yen which he could not pay. Initially, he appears in chapter thirty claiming to just want to check on his son.

Spoiler

It turns out that he has only returned to destroy Yukiteru's diary in order to fulfill a deal with the Eleventh. Despite his only clear desire being to free himself from his debts, he does try to save Yukki when the latter almost falls to his death, but takes the parachute away from Yukki before the tower crumbles soon after. He then stabs his wife when she tries to take him to the police and escapes, though is stabbed to death himself two chapters later by the Eleventh's men.

(Source: Wikipedia)