一人ひとり悦えつに入いる

expression, godan verb (-ru)

be self-satisfied; chuckle to oneself

Describes someone who is quietly pleased with their own actions, ideas, or situation, often with a sense of smugness or private delight. The phrase is a set expression and not broken down further.

• 彼かれは自じ分ぶんの発はつ明めいに一人ひとり悦えつに入いっている。

  He is pleased with himself over his invention.

• 会かい議ぎで意い見けんが通とおって、部ぶ長ちょうは一人ひとり悦えつに入いっていた。

  After his opinion was accepted at the meeting, the department head chuckled to himself with satisfaction.