[Anime Crossover] The Siscon Training Game

I bought a game called The Road to Raising a Siscon. I heard there were several worlds to choose from, and the brother assigned to the character was different in each one. Other than their personalities, everything about the brothers in the game was perfect. The player's goal was to make the brother's affection for the character reach 100 percent. I looked through the available worlds: The first one was apparently called Hunter, and the brother was the eldest son of a family. The second was apparently called Demon Blade, and the brother was also the eldest son of a family. The third seemed to be called Literary Masters, and the brother was still the eldest son of a family. #Is this game obsessed with eldest sons? [pointing accusingly]# But then I thought about it. All I had to do was train them to become siscons. It didn't seem that hard. ** Full of confidence, I entered the first world. Good news: The whole family were professional assassins with high combat abilities. Bad news: The identity I got at random was not blood-related to them. After thinking it over, I carefully put my points into beauty and combat ability. I had considered everything. Beauty would make people more tolerant of me, so I wouldn't get my throat slit one day. Combat ability would let me fight back, so I still wouldn't get my throat slit one day. But despite my careful plan, I suffered a crushing defeat. My brother, Illumi, was always saying strange things and doing strange things, so I couldn't help getting into "friendly exchanges" with him using my fists. I thought miserably, this save file is doomed. After all, what normal person would have 100 percent affection for a sister like that? [Ding! Congratulations, player, on achieving the pseudo-sibling-marriage ending and clearing this world!] Me: ...Huh?? I stared at the newly unlocked ending CG and fell into deep thought. After thinking it over, I finally understood. Beating someone is affection, and scolding them is love! [Ding! Random identity acquired: Muzan Ubuyashiki's twin sister.] I put my points into combat ability again and happily entered the second world. I sincerely thought, This time, I'll get along wonderfully with Big Brother Muzan! Muzan: ...Get lost! Premise: In a dangerous and complicated world, the bonds between family members will always shine and never go out.