The supporting character's harem is very normal - Chapter 504: The One Who Died Instead

Jiang Liu lost his father at the age of three. When he turned five, his mother decided to run away with another man. At the age of fourteen, he sent off the only relative he had, his grandfather, before carrying a small amount of property and stepping into the big dyeing tank called society.
He was stingy, selfish and absolutely disgraceful. Except for breaking the law, he accumulated all the bad habits available to the mankind. Yet, such a man, after an unexpected death, was bounded by a silicon-based creature called the righteous father’s system. Since then he started his magnificent career in the world system.

World 1: On the ultimate evolution of unquestioning filial piety;

World 2: The man who loves to boast;

World 3: The search for the second spring for ones own mother

World 4: Good father

World 5: The self-cultivation of a national husband

World 6: Acrobat

World 7: Divine stick

World 8: My home has a baby egg

World 9: The correct way of wearing the green hat

World 10: Tremble, you scum man

World 11: An angel who doesn’t like to talk

World 12: The rebellion plan of a martyr

After several worlds went by…..

Righteous father’s system 001: [Shivering], I wonder if I still have time to change my host.

- Description from Novelupdates

In her past life, Xia Chu lost her virginity before marriage and was scorned by her family as a wanton woman, forced to marry an old widower with a limp. Her aunt and mother died one after another because of her. Fleeing alone to the south to work, she suffered a hard life and eventually died tragically at the hands of a scoundrel.Reborn, she is determined to protect those who love her and those she loves, to rewrite destiny. Those who framed her, she will make them suffer the consequences; those who forced her, she will make them kneel and beg for mercy; and those who killed her, she will make them wish they were dead!By the way, that tall, stoic man with good looks, loyalty, and skills, I might as well marry you since you’ve got it all.

Side story of Kyoukai Senjou no Horizon bundled with the first press release of the 1st, 3rd, 5th and 7th Blu-ray volumes of both seasons of anime.

This side story follows Asama, Kimi and Mitotsudaira aboard Musashi one year before the beginning of the main story, as Asama is considering to create a music band together with her two friends for the next festival in Aki, a territory under the governance of K.P.A. Italia.