I gotchu...
"Sorry to keep you waiting. We finally get to sleep together..."
"Yeah, we finally get to sleep together...wait... the heck are you saying!?"
"It makes me the happiest when I get to plop into bed with you, Saito."
"Are you okay!? Did you eat something strange!?"
"If I had to say... I...
I just checked a Japanese dictionary. Despite Yamada's assertion, the word he used does, in fact, refer to both necklaces on humans and collars on animals. 🤔
(He said 首輪 (kubiwa) and she corrected him with チョーカー, literally the word "choker" borrowed from English.)
Similar to Tsukasa's regeneration ability, there's also a TV series that I loved called Forever: https://www.imdb.com/title/tt3487382/?ref_=nv_sr_srsg_3_tt_8_nm_0_q_Forever
Aaand Deadpool. :P
Yuu's like the MC of "Ikusei Skill wa Mou Iranai to Yuusha Party wo Kaiko Sareta no de, Taishoku Kingawari ni Moratta 'Ryouchi' wo Tsuyoku Shitemiru" but not in a Tolkien fantasy RPG world.