Keigo Kurusu

Keigo Kurusu (also known as the Fourth Diary Holder) is a character in Future Diary (Mirai Nikki). He is the calm and composed chief inspector (or captain) of the Sakurami City police force, around 35 years old, and a dedicated detective who values justice.

His Future Diary, the Criminal Investigation Diary (or "Investigation Diary"), predicts crimes and related events he will investigate within his jurisdiction (up to about 90 days ahead), helping him track other participants in the survival game. He has limited personal interest in winning the game itself and initially allies with Yukiteru Amano and Yuno Gasai, aiming to stop the deadly Diary Game and prevent further harm.

His motivations stem partly from his terminally ill son, which influences his actions later in the story. He's portrayed as a tragic, principled figure who starts as an ally but becomes more antagonistic due to circumstances.