N3 · Structured courses

～Koto ni Suru: Decide To

Master koto ni suru for personal decisions and koto ni naru for external outcomes. This lesson combines form, context, examples, common mistakes, and practice so you can use the pattern in real communication.

12 minNihongo Hub Editorial TeamPublished 2026-06-06Updated 2026-06-06

Learning objectives

  • Lesson goals: Master koto ni suru for personal decisions and koto ni naru for external outcomes.
  • Form and connection: [Verb辞书形/なi-adjective] ことにする
  • Nuance in real use: ことにする and ことになる mark the boundary between will and fate in Japanese — the former is your active choice, the latter an arrangement that comes upon you. The line between these lies where Japanese people divide "what I can control" from "what I cannot."

Form and connection

[Verb辞书形/なi-adjective] ことにする

Core Explanation

Master koto ni suru for personal decisions and koto ni naru for external outcomes.

Cultural Note

ことにする and ことになる mark the boundary between will and fate in Japanese — the former is your active choice, the latter an arrangement that comes upon you. The line between these lies where Japanese people divide "what I can control" from "what I cannot."

Practical examples

I decided to exercise every day.
It has been decided that I'll transfer to Osaka next month.
It is the rule here to take off your shoes.
I make it a rule to jog every morning.

Common pitfalls

Build the base form before adding the pattern

Complete the required conjugation first. Do not keep polite and plain endings at the same time.

Match politeness to the situation

The examples are reliable starting points; relationships and context can still change the most natural wording.

Practice and answers

1. Write the connection formula for this lesson.
Show answer[Verb辞书形/なi-adjective] ことにする
2. Explain the meaning of the first example.
Show answerI decided to exercise every day.
3. Rewrite the final example using this lesson pattern.
Show answer毎朝まいあさジョギングすることにしています。 ([Verb辞书形/なi-adjective] ことにする)

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