あらたarataまるmaru
1.

To transition from an old state to a new one, indicating a significant change or improvement in conditions or situations.

2.

To adopt a formal or serious demeanor that deviates from one's usual behavior, often in preparation for a ceremonial or official context.

3.

To undergo a deterioration in health, often leading to a critical condition or severe illness.

Example:

長年の習慣はなかなか改まらない。