They are all linked to Touhou Project, and this song Mews is also linked to Night of Knights. It is a fan song of Touhou Project's character Sakuya Izayoi (also known as Cheman) from Touhou Project.

This is a song from Touhou. It’s not a link between the two games, it’s a link between the game and Touhou.

Performers can read the description below.

It’s just that these two games happened to include this fan song from Touhou Project. Moreover, this song is still a big hit among Touhou fan songs, and you can also find it in many other music games.

Is there anyone who doesn’t know Dongfang? You can search it