Responses
Yup, Woo Ah-seong (or Ah Seong or Ahseong or Aseong, depending on how you romanize it). Like you said, the -ah is added to the end of his name because the MC and ML are friends, but it shouldn't remove the initial "Ah" syllable from his name, so the friendly way to call his name would be "Ah-Seong-ah" (아성아). This is how the MC calls him in the original Korean version.
I get confused with ML's name. Can anyone please tell me what is his name exactly?