Is Ivan partly alien? That would explain a lot. He has a small tooth sticking out, he can tame an alien dog, he knows how to remove a collar from a person, he has another microphone.
3:07 this flash in the background is almost mimicking the stereotypical fireworks that go off during a big kiss in hollywood films, but watchers know something bad is going to happen (im going to go cry about this)
The voice actors of these characters based on my imaginations are Minato - Natsuki Hanae (Kimetsu no Yaiba) Gyaruo - Yuuki Ono (Kuroko no Basket) Vermouth - Yuuma Uchida (Shangri-La Frontier) R-18 - Kouki Uchiyama (Jujutsu Kaisen)