東京の 公園の 池の 水が、まっ茶の ような 緑色に なりました。
大学の 研究者は、見るだけなら 体に わるく ないと 話しました。
でも、しぬと わるい においが 出ます。
Why six school grades, and not N5–N1?
Because that is how Japanese children learn to read. Japan's Ministry of Education fixes exactly which character belongs to which grade — so "grade 3" is a boundary you can verify, not a feeling. Every article here is machine-checked: if a single character sits above its grade, it is not published.
The result: you never hit a character you have not learned. That is the whole reason this product exists.