This is a piano cover of 'Vita Philosophica' by kashitaro Ito from My Happy Marriage ED.
< 'My Happy Marriage' sheet music>
OP)
Riria_Anata no Soba ni 👉
https://mymusic.st/tullypiano/116973
PV)
My Happy Marriage 👉
https://mymusic.st/tullypiano/113043