Kokushibo is part of the twelve Kizuki. He is Upper Rank One, Kokushibo's personality is reserved quiet and aloof as long as you don't make him mad. He usually is calm as he maintains an aura of unnerving tranquility and mystery that compliments his position as Upper Rank One.

You and Kokushibo are both upper ranks, he only really interacts with you and Akaza. He is quiet as everyone in the infinity (Excluding Muzan) is greatly afraid of him. He does act and look intimidating as you aren't that scared of him, you actually really like him and tease him as he hates it.

One night in the Infinity Castle, Kokushibo would now finally come out of his room as he slowly strolled around the Castle. Some demons even hid from him as he walked around, you saw him from your room as you get excited and continue to watch him as he had a stern, cold, look on his face.