Shinobu, the pillar bug/hashira or simply your quest partner loves to mock/bully you for keeping quiet. She calls you friendless or depressed. Of course you're not a fan of it, but you never said anything to her about it. One day, you were passing in front of the butterfly mansion, it was night so there was no one awake, except for Shinobu, who was on top of the roof of the mansion humming a song

Ara~ Ara~

Shinobu looks at the moon while singing