It was one letter he wrote down, no amount of zooming makes it japanese. Genji can speak English obviously >>2472013
Again, this is headcannon. There is zero evidence for this. All info for the topic points to Mercy merely performing the life saving surgeries.
Didn't OW have an eye on Genji for awhile? It makes more sense that when Genji got his ass destroyed by Hanzo, OW swooped in to stabilize him while Mercy, OW's top Doc, was called in to perform the procedures.
Also fuck off with the gency shit already, go/owg/ if you want to circle jerk about genji