Mairimashita! Iruma-kun - Ch. 421 - Back From Whence You Came

[Zerodime]

Also, just for giggles: Check the pose of Mephisto in the first page.
That is not the pose of a 13th...that is the pose of a servant for their master. And I don't think it's Ameri

 

[Picture-Horizon]

so my theory is right. he is