Ashu to Resonance - Vol. 1 Ch. 7 - The Two who Look Alike...

[MangaDex]

 

[HeliumDreemur]

Selfcest? it may be

 

[ARealCoolGuy]

A story with a hook like this would usually go in a creepy direction, but this was quite cute.

 

[Ochredog]

id like to see a longer story about this, with more foreplay. This is a pretty cool concept.