#HumanKoi (Koi's sane soul) is a very depressed soul because it's the last emotion Koi felt before going insane in the Aslyum. The last of his sanity was taken from him by death (Kohkai died) & he was depressed & that lead to insanity.
This soul is constantly crying & screaming out loud, and asking Koi to let him die, but Koi can't hear him talk unless he's hanging out of that portal that leads to Koi's souls. Problem is, He is locked inside an office which prevents this. Only Koi can open it.