Ihoujin, Dungeon ni Moguru - Chapter 141: A Respite From Adventuring III

Before Li Daniu had time to be excited about being a prince who was about to ascend the throne, he learned that his country was about to be submerged by sea water.

“Can I wear it back?”

- Description from novelbuddy

The two faced number one female spy transmigrates to a different world and becomes an outrageous idiot girl. When she woke up, what she had to face was consecutive blows of the decline of her family clan, her crippled martial skills, and her disfiguration. To protect her family, she must obtain the treasured book, obtain outstanding achievements, summon a dark beast army. Wait and see how in this unfamiliar, dark magical continent, she dies and becomes a demon then steps up to the top, making all of the formidable people in the world bow down to her in respect.

- Description from Novelupdates

Stranded in a world not his own, in a body not his own, Kaden finds himself stuck as a low rank marine in treacherous waters in the middle of an ocean where only the strongest can survive and a count down until a war that would shake the oceans and the very world itself erupts, where the kings of the sea will devour the chum. Gamer System. Insert.

A fluffy, sweet modern GL story about a mature older women and a cute university student.