Thirty Days with My First Love Sister is a fully video-based interactive romance game.

Your childhood friend and promised elder sister returns from abroad, staying at your home for a whole month before the new semester begins. Across thirty warm days of living together, you'll experience the sweet daily romance of sharing every moment with your beloved sister.

During the day, freely choose your destination from 10 main scenes — classroom, playground, amusement park, bridal shop, lingerie shop, clothing store, arcade, restaurant, gym, night market, supermarket, water park — and over 30 sub-locations, each with 20~40 AI-generated video scenes.

Every evening, you return home to spend the night with her — late-night chats, playing games together, watching TV, goodnight whispers — and intimate interactions gradually unlock as affection grows.

Every choice changes your stats — money, affection, stamina, intellect — and the total of 30 days determines which ending you reach. Friend, lover, marriage, or a hidden secret branch…

Experience heartfelt romantic moments and pure love in this relaxing journey, and write a love story that belongs only to you.

【Characters】

◆ The Sister (Female Lead)

Your childhood sweetheart and promised fiancée, who has returned from studying abroad and is staying with you before the new semester begins.

Gentle, clever, and caring with a warm sisterly charm — she is excellent at cooking and everyday life.

With her, you share both the familiarity of family and the flutter of new love.

She will be by your side for thirty days — every choice you make will shape how her heart feels about you.

【Features】

• Fully AI-Generated Video Scenes: Over 100 AI-generated video clips stitched into a continuous story — far beyond the static CG count of traditional visual novels

• 30-Day Simulation + Affection System: 4 core stats (money, affection, stamina, intellect) that change in real time and determine your ending

• 10 Main Scenes + 30+ Sub-Locations: Amusement park, bridal shop, gym, night market, water park and more — each with unique scenes

• Cross-Scene Story Arcs: Try wedding dress → Ferris wheel confession → buy ring → propose → marriage true ending

• 4 Major Endings: Friend, Lover, Marriage true ending, plus a hidden secret branch — multi-playthrough exploration

• 12 One-Time Key Moments: Ferris wheel kiss, bridal shop flutter, late-night confession, first hand-hold and more — each plays only once in a lifetime

• Anti-Repeat & Fallback Mechanism: 30 days × 30 events randomly drawn from the pool, with key moments protected

• Costume Unlock System: Buy swimsuit, gym outfit, wedding dress, ring to unlock exclusive scenes and storylines

• Multi-Playthrough Inheritance: Hidden easter eggs, affection bonus, starting coins from your 2nd playthrough

• Steam Cloud Saves: Sync your progress across devices

【About Us】

Indie Developer / Small Indie Team

This game is a single-developer / small-team production, featuring all-AI video alongside hand-crafted design, programming, art, and voice direction.

We are committed to using AI tools to lower the production barrier and deliver sweet, heartwarming pure-romance interactive stories to players.

Thank you for your support — we hope Thirty Days with My First Love Sister brings you a beautiful thirty-day journey.

【Content Disclosure】

The game features a non-blood-related childhood friend elder sister character (18+). All intimate interactions are pure romance, with no nudity, sexual hints or violence included.

【Content Warning】

This is an all-ages pure romance game. There is no violence, gore, or adult content.

The two main characters are not blood-related. All characters are 18+.

All intimate interactions are wholesome and romantic in nature.