Interesting concept, with great graphics and audio. The music changing whenever Meguri is nearby is a nice touch, too.
There's an error in the second stage (the one after the tutorial, after meeting Meguri), after inputting the passcode, which prevents progress.
An error occurred running the Unity content on this page. See your browser JavaScript console for more info. The error was:
TypeError: AudioParam.value setter: Value being assigned is not a finite floating-point value.
unityFramework/jsAudioCreateChannel/channel.setPosition@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
_JS_Sound_SetPosition@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
_JS_CallAsLongAsNoExceptionsSeen@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
callUserCallback@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
runIter@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
Browser_mainLoop_runner@https://html-classic.itch.zone/html/19116348/LastColorWebGL/Build/LastColorWebGL...
Also, "immediately" is misspelled in the intro.
Unfortunately I couldn't get past that stage due to the aforementioned bug. Looking forward to whenever it gets fixed though!