@Aifaix I said I wouldn't react to this thread anymore, but you seem to want to be factual so I'll engage.
Before you start calling people morons you should start by getting your own facts straight and you can do that by taking the two very first links in a search engine. Yes, the legal age of consent in Japan is 13 for both boys and girls if we don't take into account local laws actually raising age of consent to 16 or even
18 in Tokyo, and only if the older person isn't in a position of force or trust, or abuses their inexperience. In the case of Sayu, while she does meet legal age requirement, she doesn't meet Tokyo's, and both parties don't have an equal position in the relationship. In the case of her past sexual favors, the men abused their position as they provided shelter and, maybe, abused her inexperience as she didn't know what they were doing was not okay (? actually not 100% certain of this part and cba looking for the chapter). In the present case, even if she were to have sex with him, her verbal consent is null and void as it happens under threat and coercion. All of these interactions are a straight ticket to the cops.
It's not rape as everyone pictures it with some disgusting dude sweating on top of a crying girl, but it is, very objectively, statutory rape.
https://en.wikipedia.org/wiki/Ages_of_consent_in_Asia#Summary
https://en.wikipedia.org/wiki/Ages_of_consent_in_Asia#Japan
https://www.ageofconsent.net/world/japan