Completing the Secret Event on The Mimic
as shown on thumbnail, you get after collecting 30 souls from Shinigami. You need to encounter Aka Manto in order to enter Shinigami's dimension(?). You have a 1/4 or 25% of encountering it.
I'm sorry for the lack of content today, I just really didn't feel like uploading things to my channel. But here's a video I can give to you guys!