Masato Aisaki is the Emiru Aisaki's brother. He's seen as someone controlling, bossy and selfish at first, which causes big tension between Emiru's friends and him, but after his Oshimaida transformation, he makes an honest effort to accept his sister's choices and even lets her play her guitar at home. He seemed to have been more accepting of not only Emiru but of Henri as well. They have been seen chatting and walking around happily during the summer night festival. He is also shown to be caring and supportive, as he defended Henri's privacy, and encouraging him to do his best by holding his hand when Henri was doubting himself. 

Voice reference: https://www.youtube.com/watch?v=xTCgv5PU4bA

· Appeareance: From episode 15 to 49