Request Novels where MC's identity changes.

Like, transmigration or physically changing into a new person. No reincarnation though. Also no isekai transmigration. Whether they're in a fantasy world or modern world, a novel where they remain in that world even after changing.

The best example of this would be a lot of gender bender novels like Reborn as My Love Rival’s Wife where the main character finds himself waking up as a random girl or like Maou ~ Sou da, Yuusha wo Yome ni shiyou ~ or Kanojo ni Naru hi(manga) where they physically transform into a new person; a girl.

Know any novels like that? As I said, this can basically be found in all gender bender novels but I already know about every gender bender novel on this site so recommend me something other than gender bender (cause recommending me gender bender is just pointless at this point).
Also, no harem!

So, basically a novel where the MC irreversibly changes into something or someone else without being transported to a different world.

 

I wanted to suggest Lord of mysteries, then I read description
ಠ﹏ಠ

 

Just in case you didn't read it, let me recommend The Scholar’s Reincarnation (the manga or the novel raws since not that many chapters been translated from the novel)

 

I don’t think there’s any novel that has the Mc physically change without isekai or gender bender but I have :

I’ll live my second life
MC is a princess that’s neglected but she escapes and joins the army and now goes around as a (scrawny and delicate looking) guy. Fear not, there’s not a single “kya hot guy protecting me doki doki” moment and she really does intergrate as “one of the guys”. Theres one scene were she’s basically doing yoga and showing off flexibility and all the guys are just freaked out a la “bro spines aren’t meant to bend like that wth!!!”. Her looks are only mentioned cuz she’s offended no one thinks she’s manly.