Even Though I Was Reincarnated as a Side Character, Is It Okay for Me to ‘Capture’ My Younger Sister (the Heroine) and Make Her Happy?

Before I knew it, I had been reincarnated as a man named Eiji Kanzaki, who appears in the game “Koiiro ni Somaru Sora.” Eiji is just a side character, the brother of the heroine to be captured. I never expected to be reincarnated, and as a side character at that… I thought I should enjoy my second life without causing any trouble. However, my stepsister and one of the heroines, Suzuna, seems to be suffering greatly. In the game, Suzuna is saved by the protagonist three years from now. Should I just leave her be until then…? No way, that’s impossible! Even if I’m not the protagonist, as her brother, I will somehow help Suzuna—thus begins the struggle of the side character, Eiji Kanzaki!