Halcyon Days ~Sunny Days with Sister-chan~ is a point-and-click RPG Maker game by CatNight, presented with 2D CG artwork. You play as a man who washes ashore on a quiet beach and is rescued by a kind nun called Sister-chan. The story follows their shared daily life during spring, combining cohabitation and touch simulation. Core themes include romance, religion, and corruption.
The current build is v1.0.4, released on September 14, 2025 for Windows, in English (GLM-5), and it is censored with mosaics. Development appears ongoing, as the update fixes a relationship problem that could make Sister-chan react extremely negatively when going to town. Several issues remain under investigation, including problems in some scenes, simultaneous outcome tracking, and dialogue reverting to calling her older brother.
Developer's description
You wash up on a quiet beach, barely conscious, only to be found and taken in by a kind-hearted nun known only as Sister-chan.
This is a cohabitation touch simulation game that gently unfolds your daily life together under the warmth of spring.
Halcyon Days ~Sunny Days with Sister-chan~ screenshots
Download Halcyon Days ~Sunny Days with Sister-chan~ v1.0.4
v1.0.4
Fixed issue where relationship with Sister-chan would become extremely negative when going to town
【Bugs and Issues Under Investigation】
Unable to perform insertion during the second forced assault
creampie not counted when reaching climax simultaneously
Reverts back to calling "older brother"
We apologize for the inconvenience.
v1.0.3
Fixed ending not triggering
Fixed fewer choices appearing when climaxing simultaneously from behind
Fixed Sister-chan remaining asleep
Fixed remaining asleep when starting touching via "invite to H"
v1.0.2
Fixed receptivity being locked at 100
Fixed incorrect messages when walking in town
Fixed items being usable multiple times
Fixed 20,000-yen items not working correctly
Fixed Mamushi Drink not being released
Fixed character becoming depressed when inviting to H
Fixed insertion gauge not moving
Fixed unexpected messages during touch movement
Added wait time to touching to prevent crashes from rapid input
v1.0.1
Fixed screen darkening and progression halt when selecting "time to go home" on a day off
Fixed ending replaying after waking up in the morning
Fixed vaginal ejaculation count not increasing beyond one in erotic scenes
v1.0
Initial Release
Player reviews
Player rating3.0 / 5 · 1 ratings
Written reviews1 · avg 3.0★
Positive (4–5★)0%
Latest review2026-05-07
DrWeeb2026-05-07★★★★★
I played this a while ago so my memories are a bit fuzzy, but from what I remember, it's average/OK. Nothing special. It's your average co-habitation game. You spend your time working to make money, buy ingredients (your meal plan)…