FUTABA
'Yuhi told me, 'I, even now, am serious about you. You'll probably have to deal with me and my selfishness. I'll probably make you cry even more. But, I love only you. I can sell my body to as many women as I want. But you're the only one who has my heart. That's why, turn around already. I didn't get a good look at your face just now with the others here. Let me see you, Sumire, I've missed you so much.'
Naive Succhan, anyone can say those words.
Anyone can say it. Her best friend must have known that and that's why she took that out. Terashima's family symbol, the earring that you give to your partner when you're married or engaged. Although Succhan cannot wear it due to her engagement with Soujiro, the fact that he gave it to her must mean that he's serious.
It's naive, but she wouldn't have accepted Terashima's offer to be a member of the same unit if she thought he was a bad person.