Akito has a mgawanyiko, baidisha personality and his darker side is called Agito anime: Air Gear
pic: left is Akito (the happy side), he got that name when he was born and right is Agito (the dark side), Akito had a mgawanyiko, baidisha personality so that's why he has a eye patch when the eye patch is on his right eye he is Akito and when he change the eye patch so it on the left eye he becomes Agito, the eye patch makes him be able to control his mgawanyiko, baidisha personality (?)
Ryo Kurokiba from chakula wars b'cuz everytime he uses his headband he looks like a scary devil when it comes to cooking but when he get it off he is just like a boring normal person
He normally seems like that quirky, funny, happy go lucky guy, but he's actually...y'know...a demon- So he tends to have little moments when he seems very unsympathetic and unemotional, such as not batting an eye and keeping a smile after revealing Amaimon impaled on iron spikes to the reader. Although he doesn't really snap at all and go killer psycho crazy like all other cliche anime crazies, he does have his...erm...moments.