The meanings of “see you again” and “farewell” aren't the same. Rei Furuya knew that. So if it meant “see you again,” then Hiro was going to see certain people, right? Hiro, once you've seen them, you have to come back and find me! Rei thought angrily. When you get back, I'm going to give my childhood friend a good scolding. But after his identity was exposed, Scotland was brainwashed by Karasuma Renya and turned against the police, though his love for his childhood friend remained unchanged. So Rei Furuya joined a group of people he didn't even know, embarking on a long journey to bring the good-hearted Hiromitsu back through their memories.
Theme: “See you again” means both looking forward to meeting again and going to see someone once more. Rei Furuya is the person Hiromitsu Morofushi both hopes to meet again and wants to see one more time.
Seeing the children working so hard to help makes my heart warm.