At the end of the first volume after Kazuki wins his first true battle alone. Kazuki defeated Kawazui, but passes out from exhaustion. He wakes up in Tokiko's lap (lucky bastard), and as she smiles, she tells him, "You've grown a bit stronger." Given that becoming stronger to protect everyone is Kazuki's goal...
The space rescue scene: Kazuki and Tokiko are finally reunited, and promise that rather than dying together, they'll instead LIVE together.
"If you die, I'll die too... No. I want to stay alive, next to you. We'll never be apart again. [they touch their hands] Now and then... You and I... are one."
Kazuki and Tokiko delivering the flowers from Mahiro and Co. to Ouka.
Kazuki: You know, once you get better, we should all hang out sometime. We're your friends now. You don't have to be alone anymore. We're here for you.