Well...i know Wind and Bp already answered with HTT and Maki....but 你 know what? I'm still gonna post a picture of Maki,because i can! >:D
Anyways,if 你 want to know (aside from the answered ones) then: Sketchbook-Guitar,Bass and Drums [Sket Dance] Kanade Tachibana-Piano [Angel Beats] Chihaya Kisaragi- Good Singer [Idol M@ster] The girls from [Sound! Euphonium]- They play brass instruments...or Euphonium,i guess.
Allen Walker from D.Gray-Man he is very talented. Once 你 watch the video 你 will see and hear how beautiful sounding the 音乐 is that is coming from the 钢琴 that Allen Walker is playing. Sorry there is no English Dub for this part. Only English subbed Japanese with English subtitles. 😍💖.