A JLPT quiz engine that explains the learner's mistake. The claim being demonstrated is not that it can answer — it is that the provenance of every explanation is on the screen: what was retrieved, how confident the match was, what the generated text cites, and what five deterministic checks made of it. You do not need to read Japanese — the scores, the checks and the three-run comparison carry the argument on their own.
Two real past-paper questions on the same pipeline. The only difference is whether the 53-card table happens to cover that grammar point — one is covered, one is not, and the page says which.