Your Highness, Proton, Is Here to Eat Some Sweets.

The third princess, Su Xunyue (the heroine), is a laid-back, charming and transparent daughter. At first she treats the male protagonist (Wen Jingci) as a new toy, but she gradually becomes more sincere. The male protagonist went to the country of Su as a hostage when he was sixteen years old. He was tolerant and reserved. In this country where everyone looked down on him, only the female protagonist was willing to talk to him and was slightly attracted to the female protagonist.