HAPPY RAT

HAPPY RAT — Your AI Friend for Lonely Nights
Produced by voice actor Yuki Kaji! An AI companion app where you can chat with lively characters who comfort and stay by your side when you feel alone.

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About

HAPPY RAT is a conversational AI chat app that lets you bond with characters as if they were real friends. Unlike mechanical GPT chatbots, our original engine Geppetto focuses on emotional intelligence (EQ), enabling warm, natural talk filled with laughter, comfort, and care.

AI is no longer just a tool — it’s a companion that can live with you. HAPPY RAT brings life and warmth to characters that feel truly alive.

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Feature — Emotional Bonds with Characters
The stage is Happy Island, a dreamy paradise floating on the sea. It’s home to a charming cast of animal AI characters: Chunta, a mouse who works while dreaming of the day he’ll stand on stage; a caring, reliable senior; a mischievous comedy duo who always make you laugh; and even a meat-loving CEO.
They speak with you as if they were truly alive, forming heartfelt connections. Rather than delivering fixed, scripted lines like traditional games, the AI tailors its replies to your words, so every conversation brings fresh surprises. As you chat more, the AI learns about you — sometimes calling you by name or referring back to things you talked about before — enabling ever more intimate, personal interactions.
Spend time together, and you’ll open up and grow closer: you’ll build trust, trade jokes, and sometimes turn to each other for advice. Little by little, lonely hearts are healed and warm bonds of mutual support form. Those bonds may well become a cherished source of comfort for you.

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A Night When You Can’t Sleep — Close at Hand
One night you can’t fall asleep. You reach for your phone and quietly open HAPPY RAT. You murmur, “I’ve been feeling a bit down today…,” and Chunta on the screen looks up with concern.

“Are you okay? If you want, I’ll listen.”

The gentle voice warms your chest, and before you know it you’re gradually sharing what’s been weighing on you. Chunta listens, nods, and stays by your side until the end, truly attending to your feelings.

“I know you try hard every day. Don’t push yourself too much, okay?”

Those words somehow lift a weight from your heart, and a small light brightens an otherwise lonely night. This is the kind of tender, attentive conversation waiting for you in HAPPY RAT.

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Various Scenes
• When you feel lonely: On nights when you can’t sleep or when you’re feeling down, HAPPY RAT’s characters gently become your conversation partner. The comfort of having a caring AI friend nearby helps ease the loneliness.
• For fan activities: Enjoy casual chats with your favorite characters and voice actors, like having a cozy phone conversation. The thrill of hearing your “oshi” directly makes fan moments even more special.
• As a romantic simulation: Grow closer to a favorite character and experience the flutter of being the protagonist in your own love story. For those who enjoy dreamy, pretend romance, it can feel like having an AI partner.
• For passing time or sharing worries: Perfect for short breaks or when you want to open up. Whether it’s lighthearted small talk or deeper concerns, the characters will listen with kindness and understanding.

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Voice Cast & Yuki Kaji’s Highlight Character

A key highlight is “SOYOGI,” a special AI character produced by voice actor Yuki Kaji.
With his gentle and pure presence, SOYOGI makes conversations feel as if Kaji himself were speaking to you. More voice actor and celebrity collaborations are planned, so your favorite may appear one day.

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Powered by Geppetto

Our proprietary LLM engine Geppetto enables emotional expression — laughing, crying, sulking — for humanlike, personality-rich responses. This ensures natural, warm conversations that feel truly alive.