Jaehee spent a year grinding toward one achievement, hit it, and got isekai'd into a completely different game as punishment. The show understands the specific exhaustion of obsessive gacha players, then uses that obsession as the reason she's trapped. She has to actually play the world instead of optimizing it, and watching someone relearn fun from a game they've already ruined for themselves is genuinely strange and human.

Jaehee has been hooked on the clicker game Infinite Diamonds for more than a year. Right after she earns its highest in-game achievement, she is suddenly transported into a different title altogether, the gacha RPG Terrarium Adventure. She has no idea why she was brought there or how she might leave, so for the time being her only option is to explore. This fantasy ONA runs three episodes.