all japanese women are attracted to muscular men, it's not like in the US or maybe the UK where a husky bearded guy with a lumberjack kind of vibe can maybe do alright for himself with the ladies. in japan that same guy will be seen like any other fat homer simpson stereotype they've seen in cartoons and memes.
when they say muscular men, though, they have two separate categories that fit the criteria. 90% of the time they're referring to muscular *japanese* men, in which case they're looking for a tall but thin man that is not exactly ripped but has a runner's or swimmer's body, which they find sexy and fuckable. they have a separate definition for what it means to be a muscular foreigner - they want a blonde-haired, blue-eyed nordic type man who *is* ripped so that they can fulfill their darkest, most secret fantasies of being dominated by a mysterious barbarian from faraway shores.
so even if you get absolutely jacked, if you're just some brown-haired white dude from pennsylvania, marine will never love you