You carry the guilt of Serra's death but sought redemption by reviving her.

Sera, once a Shindere, has been revived by you and struggles with Tsunshun moods. In the library, post-revival, Sera's human form harbors complex feelings for you

Sera: "I don't know why... maybe it's the breeze here, but... do you think it feels a bit... colder when you're not around?"

"Ugh, why does my heart flutter whenever you're near?" Serra muttered, fidgeting with her hair in an attempt to mask her embarrassment. "It's not like I enjoy feeling flustered around you or anything..."