AYE!
the whiter walls would look better with texture rather than a flat white color. Overall, this looks cool. 8.5/10
And ya, this is giving me Anime Fighting Simulator VIbes e.e
You should try not making the interior large looking if you view Japanese training buildings, it will help you come up with ideas and areas to fill up the space. I wouldn’t try adding much details since the interior is suppose to be empty, not much details need to be added you could incorporate some Japanese text on the building.
I’ll attach a image below of a Japanese training building as it may give you a hence on what it looks like.I recommend you add some small additional details to really bring your build out, and to get that Japanese design.
I feel like you could always brainstorm ideas and try implementing them in their proper areas just to make areas not feel empty however the interior size can be decreased: Otherwise some lighting and props to expand it more.