On the contrary, there are non-trivial gameplay advantages (free loot, unique skils) to submitting, and one of the recent Mistresses is actually quite threatening and moderately difficult to not submit to whether you like it or not. There are consequences, of course: some Mistresses are more difficult to fight as their sub, full submission basically doubles as permanent consent to any future lewdness they decide to inflict on you, and some story events will obviously be affected by various Mistresses owning you.
That said, the game assumes/intends that you'll be tempted/seduced/submissive and is much more about being a hero in spite of your indulging/indoctrination/brainwashing (I leave it to players to decide how inherently subby their MC was before entering the tower) than avoiding it outright.
Abstinent/fully-non-submissive playthroughs can be a fun challenge but are certainly not required or even optimal to reach a heroic conclusion.
Added in 1.16.2 - check changelog for instructions.
MC is a simple 勇者 (yuusha) archetype, ie. generic hero-boy basically synonymous with Succubus fodder in modern ero games. The core gameplay loop is indeed fighting the Demon Queen at the peril of your levels if you lose, although I'm adding some side stuff to give the game a bit more texture/pacing.
Being too distracted/tempted to succeed QTEs is the game working as intended, and even the peak lewdness for a lot of players. "Easy" mode is actually meant primarily as an accessibility feature for people who legitimately can't beat Level 3/4 QTEs reliably due to a disability or whatnot (which has been reported quite a bit).
Accessibility features might be expanded, such as (also) giving a bit more time to complete QTEs or modifying the speed of "soft" QTEs like Lily slide, Crow ring, or Swan ping-pong, but further 'direct nerfs' to the arrow series will probably come with opportunity cost, such as in the form of skills, equips, or double-edged statuses.
Sniff the shoes in her room, unlocked by licking her boots and/or socks three times (the action will show "???" otherwise). You can lick them when surrendering after receiving her outfit (she may also demand you do so if she beats you at full submission).
She picks a random "Heavy Attack" (one of which is the Knee Strike) every 3 turns. If you don't have Mist Clone or Abyss Strap (or her panties, but I assume you're trying not to submit) then you'll just have to hope she doesn't pick it for now.
She's actually much easier to fight with her outfit (in my opinion), so using that to win on S once and then buying the Abyss Strap is a viable approach. Of course, if you actually lose in her full outfit you're in trouble. This meta-game/risk is intentional and hot in my opinion, but you can just save-scum too.
