This music piano plays when a Darkness modifier has been enabled.
SOURCE: https://www.google.com/search?client=ms-android-tmus-us-revc&sxsrf=APwXEdcxgbE1wa4JdcDb9P2FryPZh_hecA:1680818684884&q=a+deep+voice+by+myuu&tbm=vid&sa=X&ved=2ahUKEwi-r5PFoZb-AhUWjIkEHe3LCakQ0pQJegQIDBAB&biw=400&bih=738&dpr=2.7#fpstate=ive&vld=cid:fa13c5a8,vid:m8L4mfRUU1E
