After completing all endings, return to Chapter 5 (the shared bath scene). A new dialogue option appears: "What if...?" This triggers a 4P dream sequence with all three heroines. This is the final unlock.
Enhanced audio featuring full voiceovers for all major characters, deepening the immersion of the emotional narrative. Sisters -Natsu no Saigo no Hi- Ultra Edition
The Ultra Edition is not just a re-release; it is a technical and artistic overhaul. Released a few years after the original standard edition, this version is designed for players who want the highest possible fidelity. After completing all endings, return to Chapter 5
Start │ ▼ Ch 1-8 (Common) │ ▼ Ch 9 (Peeping history determines route) │ ├─── Peep Ryou x2 → Ryou Route → Ryou End │ ├─── Peep Satsuki x2 → Satsuki Route → Satsuki End │ └─── Mixed / Default → Ryou Route (then replay for Satsuki) │ ▼ [After both sister endings] │ ▼ New Game → Ch 2 → "Stay with Miki" → Miki Epilogue → True End │ ▼ Return to Ch 5 → "What if?" → 4P Dream Scene │ ▼ 100% Complete Enhanced audio featuring full voiceovers for all major