Tate no Yuusha no Nariagari - Chapter 361 - An Enemy of an Enemy is

Yu Shanshan, who has been tyrannical and lawless for 20 years, suffered retribution at the age of 21. She changed from a little ballet princess of 45 kg to a poor and fat one of 90 kg.. Apparently, eating was the most important thing in her life. Her success in losing weight was far away.

However, one day, the father of her child who had disappeared for four years came back. From then on, Yu Shanshan was forced to embark on a diet that was worse than death.

- Description from Novelupdates

In a galaxy far away, there is a kid without innate ability to practice internal techniques. So, in order to gain the respect of his father, he resolutely chooses to follow the more difficult and painful path of practicing external techniques. As the years go by, he grows up, but what really changes his life is a mysterious meteoric crystal stone – the Meteoric Tear. This stone fuses with the young man’s body unnoticed, and he seems to undergo drastic transformations as a result. After that, everything is changed. Eventually his father knows that the son for whom he hasn’t really shown a lot of consideration possesses astonishing abilities. And there’s a lot more to come.

In the Year 2030, the ground-breaking online game «Divine Realm» shook the whole world. Its system of allowing players to exchange in-game currency into real-life money attracted everyone’s attention.

The male student, Fukai Nagamasa, ignores his studies for college entrance exams in favor of following the path to chuunibyou. As he fainted during night cramming session before the exams, he realized that he was transported to a parallel world as a feudal lord in the Sengoku Era. Not to mention that suddenly, he was marrying the sixth Demon King, Oda Nobunaga’s little sister, the one who was purported to be an unrivaled beauty?