She was born in Ageo, Saitama,[1] and began judo at the age of a second grader.

[1] She entered the Komatsu Limited after graduating from Saitama University in 1998.

In 2000, after Tamura won gold medal at Olympic Games, Nagai retired.

As of 2008, Nagai coaches judo at Komatsu Limited, and Ayumi Tanimoto, one of her pupil, inherits the skill of Uchimata that Nagai was good at.

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