Everyone knows it's Reimu, and Marisa is like...she's like... more than a sidekick, but not quite as definite a main character as Reimu. Not really sure how to describe her.
But why?
Sure, reimu was the only playable character for the first 2 pc-98 games, but that's it... The first of which has barely any recognition at all, and the 2nd, has virtually none other than Mima fanboys, references to mima fanboys, and this forum's reference to Rika, and I don't think I've ever bumped into a reference to Rika anywhere else. Ever since then, Marisa has been the other playable character! (except when Reimu hasn't been either, like with double spoiler, the aya game before it (brain fart, forgot the name.. supernatural phenominon? or is that the fighting game? gah), cirno's game (which has more marisa than reimu but I digress), etc.
Am I missing why Reimu is considered a main character more than Marisa other than those 2 games which everywhere else seem not to even count? I know Marisa isn't forgotten or overlooked or anything, everyone knows and respects her status in the Touhou universe, but she's still noticeably less than Reimu IMO, and when looking at my train of thought above, I don't really know why. I don't follow the manga or anything so maybe it's obvious there, I'm asking more than trying to challenge anyone.