One bad thing about Japanese society is the high suicide rate.
One really negative thing about Japan is the high number of people who take their own life.
1) One bad thing about Japanese society is the high suicide rate.
「日本の社会の悪いところの１つは、自殺率が高いところです。
the high suicide rate で「自殺率の高さ」
2) One really negative thing about Japan is the high number of people who take their own life.
「日本のとても否定的なところの１つは、自殺する人の数の多さです。」
「自殺率の高さ」を the high number of people who take their own life とも言いかえれると思います。
ご参考になれば幸いです！
日本 
