The Japanese word for “healthy” is けんこう in hiragana, and it is written as 健康 in kanji. It can also appear as 健康な when used as an adjective, meaning “healthy.”

Simple forms

  • けんこう = health / healthy.
  • 健康 = kanji form of “health/healthy.”
  • 健康な = “healthy” as a descriptive adjective.

Example

  • 健康な人 = a healthy person.

TL;DR

If you want the hiragana only, use けんこう.