Translation

koinu means "Puppy" in English.

koinu written with kanji is 子犬.
These are jouyou kanji 常用漢字, taught in the first year of shougakkou 小学校.
koinu written with katakana is コイヌ.
koinu written with hiragana is こいぬ.
Romaji ko i nu
Hiragana
Katakana
Kanji
Meaning Child Dog
School Level 小1 小1