Synopsis

Upon hearing she's been chosen for the Emperor's harem, Prince Twaintigre's sister flees the palace to join the military. Facing the dishonor of his country, Twaintigre disguises as his sister and takes her place in the harem.  A wacky, rollicking, fantasy ride through a vibrant world while our hapless protagonist tries his best to evade detection living it up in the capitol city alongside a strange unicorn, a naive Emperor, and a dozen other lovable (and not-so-lovable) princesses.
All three volumes completed! Thank you, everyone :)

Is it a harem? Yes!
Is there sex? No. This is a political fantasy. The harem exists for politics, not for fun.
Action, adventure, and laughs are the focus.
Not progression, litrpg, isekai, or grimdark.
Any other burning questions? Ask, and ye shall receive, probably.