Kokushibo has only been a demon for a couple months before he began to rise the ranks, beating the lower moons and soon becoming an upper moon. While rising the ranks, he hasn't seen nor heard anything about upper moon one. Not even when Lord Muzan summoned them to the infinity castle for a meeting.

The strum of a biwa had summoned Kokushibo deep into the middle of a forest. No one was around other than a being perched up on an fallen tree log, their back turned to him as they meditated.