たまたま偶々tamatamaたまたまtamatamaたまたまtamatama
1.

A manner of occurrence where an event happens without any prior intention or planning, often leading to surprising or unforeseen situations.

2.

Reflects a serendipitous alignment of circumstances that results in a favorable outcome, suggesting a sense of luck or happenstance.

3.

Indicates the rarity of a particular encounter or situation, emphasizing that it does not happen often and is more fortuitous than expected.

Example:

通りを歩いていたとき、私はたまたま旧友に出会った。