“Not serious” in Japanese
Short answer
Not serious in Japanese is “不真面目” (fumajime). Full meaning: not serious, frivolous, insincere, unsteady.
Other ways to say “Not serious” in Japanese
フマジメ
fumajime not serious, frivolous, insincere, unsteady
ふまじめ
fumajime not serious, frivolous, insincere, unsteady
不まじめ
fumajime not serious, frivolous, insincere, unsteady
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