Akuyaku Reijou ni Nanka Narimasen. Watashi wa『Futsuu』no Koushaku Reijou desu! - Chapter 195.1: Speaking of Summer…

Lou Yao Yao wasted her life fighting over a man, only to find out he wasn’t worth it in the end. Because of this man, she accidentally killed her rival in love, and even ruined the man who had always been watching over her.

Getting reborn as her 20 year old self, there is still time to fix everything. Lou Yao Yao decided to live as a genuine vicious woman. After getting her hands on the loyal like-a-dog man, she would show that cheating couple what pure loving affection looked like.

- Description from Novelupdates

The romantic comedy light novel series centers on the gaming lives of various high school students who play video games, including: Keita Amano, a lonely young man who loves video games; Karen Tendō, the beautiful president of the video game club; Chiaki Hoshinomori, who constantly fights with Keita; and Tasuku Uehara, who puts on a facade of being satisfied with his life in the real world, but he in truth loves video games.

I fell into a game world out of nowhere with an instant kill skill.
And then somehow, I became a bigshot.

A world from another dimension suddenly appeared in the Milky Way galaxy and collided with the earth. A spatial collapse occurred, which allowed the monsters crossing over from the other side to invade various countries, and the earth fell into great calamity.

The military was powerless against the invasion because modern weapons didn't work against monsters from another world. Under the desperate situation, a god-like figure appeared and bestowed blessings upon the humans to awaken their power. From then on, the earth regained its hope, and these extraordinary people were called Realizers.

Tenku Okuihara is a five-year-old boy who dreams of becoming a Realizer to protect the world and his family. But an incident changed his life goal from a hero to a grim reaper.