Until Then, Your Life Is In My Hands

[ You made flowers grow in my lungs, and although they were beautiful, I couldn't breathe ]

Hanahaki Disease au in TeruSai, where Teruhashi's understandably unrequited feelings, brings her expected long lasting glorious life of fame to a standstill.

And, in response to the girl's unwavering determination to keep her memories of being in love with him to the extent of facing death, Saiki is
forced to face her with the same sentiment as he is now obligated to keep using his restoration power to turn back time on her deteriorating body.

If need be, he will keep at it for the rest of their lives.