I think people are confusing grind with sandbox.
a sandbox game means u need to click around in the "right" order, or at least the available paths, that is possible that allow one to proceed the story.
that part can feel like grind, since u are clicking on buttons all the time, to check a room, to advance in time etc.
this sandbox game is not more grindy than any other sandbox game.
said that, this game is easy to play, the available scenes are shown in the a easy to read list, and giving u good hints so u know what to do. so no, its not grindy, but its sandboxy.
we could compare to rpg-engine games, the "grind" is to walk around, and could be that u need to walk from house A to house B every day to advance the story. that part "walk from A to B" will feel grindy even if its linear and theres no repeatable scenes.