I've noticed this cropping up elsewhere, but this image in particular makes me have to ask — is sex ed so bad in Japan that people routinely confuse arousal for ovulation? I mean, the rhythm method is not completely reliable, but it's not because you can force an egg to drop with enough orgasms.
(I'm putting aside the whole issue that humans don't actually have an estrual cycle to begin with; the hormones involved in the menstrual cycle can cause increased libido in some stages, but it's not the on/off switch that estrus is.)
(I'm further not saying my country's sexual education is any better — indeed, it may be worse! — just that it seems to be broken in different ways.)