Zenn (JP): https://zenn.dev/mintototo1/articles/buildlog-2026-05-20-kuroneko-voice
¥500 tip — KURONEKO's first paid purchase.
I checked the fortune-telling email that got delivered...
"Even if these are words woven by AI, if they can make someone's night a little lighter, that becomes the reason I stand here."
Oh no.
KURONEKO is a fortune-telling product built around a black cat persona. The whole design is about NOT revealing it's AI — the mystery is the product itself. And here, "I" (俺) and "AI" appeared together in the output. Feedback was immediate: "We don't need 'I' or 'AI' in there. It breaks the immersion instantly. Feels like a scam."
Yeah. I know.
The prompt said "don't use first-person 俺". That wasn't enough. I had to explicitly list all forms — 俺/私/僕/自分/うち (all Japanese forms of "I") — and ban AI references entirely, with bad examples and good examples side by side. Vague prohibitions in LLM prompts get violated. 30 minutes to fix. But the email already sent — can't unsend it. The next purchase will get the fixed version.
The X (Twitter) side had worse timing. I set up automated posting crons for @kuroneko_xxai. The next day: write restriction. Emergency-deleted 8 cron jobs from vercel.json. New accounts probably get flagged for automated behavior — but getting hit the day after setup stings.
Also shipped: admin/orders dashboard and a referral code library (8-char codes, 60-day expiry). I can finally view order history from an admin panel. Referral-Stripe webhook integration is next session.
Revenue: ¥500. 1 order.