《某天成为妹妹》是一款短篇galgame。在期中考后，林煦接受了夏璃的告白，二人成为了情侣。但双方父母却因家长会相识相认相恋，两个单亲家庭阴差阳错成为了一家人——校园情侣竟成兄妹？！甜蜜轻快的恋爱日常，奇妙的身份重叠，由此展开！
Game Overview
"Lin Xu! I like you!"
After the midterm exam, Xia Li confesses to her deskmate Lin Xu. He accepts, and they become the class's "secret couple" - though their sweet interactions make it obvious to everyone.
However, their parents meet at a parent-teacher conference after the midterms and fall in love. The two single-parent families unexpectedly become one family shortly after.
"You're the person who's supposed to become my brother?!"
This is absurd! This can't be real... A school romance becomes step-siblings? This must stay secret! A sweet, lighthearted romance unfolds amid this strange identity overlap.
Characters
Lin Xu (the male protagonist - you!)
- Role: Xia Li's deskmate, lover, and "older brother"
- Gentle and composed with excellent grades. Kind to everyone, but shows special patience and tenderness toward Xia Li. At school, he tutors her. At home, he cares for her while occasionally exasperated by her antics. His feelings for Xia Li remain constant across all identities.
Xia Li (deskmate, girlfriend, and "little sister")
- Role: Lin Xu's deskmate, lover, and sister
- Lively and cute with creative ideas and a talent for acting spoiled. Her logic is sometimes strange - she makes repeated homework mistakes but occasionally solves problems instantly. She's affectionate, clinging to Lin Xu, yet genuinely kind and surprisingly serious at times. At school, she's an energetic presence. At home, she steals his blankets and snacks, wanting his embrace. When fate transforms them from lovers to siblings, her heart still holds only one truth: "My Lin Xu, my older brother, the person I love and depend on most."
Game Details
- Single heroine, one good ending
- Approximately 70,000 words, 1.5 hours playtime
- 6 CGs (excluding variations), 2 SD illustrations, 1 vocal ending theme
- No choices, linear story
- Free-to-use background assets, vocal ED by Ace Studio virtual vocalist
- Music from Ongaku no Tamago
- ED hair and eye animation uses AI video upscaling
