"Yukino! My big brother is in love with Yukino!" Little Kimika Keyes whoops with delight, which of course only throws Peter deeper into misery. Kimika is 10 and he's 14 — he should have the upper hand, but there is in her a bewildering mix of yōchi (幼稚, childishness) and seijuku (成熟, maturity) that forever kōsansaseru (降参させる, defeats) him.
Ana ga attara hairitai (穴があったら入りたい, He is ready to sink into the ground) for haji (恥, shame). Suddenly a thought strikes him, overpowering in its novelty: "Why don't I tataku (叩く, give her a good smack)? Just once, not hard, to teach her a little sonkei (尊敬, respect)." For a moment, he forgets about Yukino, his love, and his shame.
It seems an astonishing thing — he has never, ever, not once, raised a hand to her! Of course, it's hazukashii (恥ずかしい, embarrassing) to hit a girl, especially one so much younger than himself; on the other hand, doesn't a parent slap a child for the sake of kiritsu (規律, discipline)? Just once, to teach her. After that, it will never be necessary again.