[Kase Atsushi] Kuro Ageha - Chapter 046 [2017-11][TG]
 

[Kase Atsushi(加瀬あつし)] Kuro Ageha (くろアゲハ) - Chapter 046 [2017-11][TG]

Serialized on:

Gekkan Shonen Magazine (月刊少年マガジン)

A spin-off of a long series titled Chameleon, about gang leaders with lots of whacky events, relatively normal until the first attachment.

The protagonist Hoshino Eita (Eeta) crossdresses under the name of Eira (Ayla?), sometimes his friend Miyabi takes the place of Eira in order to cover his identity.

With that explained, Eira -> bathroom -> Eita -> TG, there is no DTG or PE.

Given the title of the series this has to be a play on metamorphosis or a butterfly effect, Eita previously smacks a young boy in the head (I can't tell if it was his past-self or relative) which causes the mark on his hand.