tatsutatsu
1.

To assume a vertical position, rising from a seated or lying posture, typically with the body straight while maintaining balance on the feet.

2.

To occupy a specific location in an upright manner, often implying a state of readiness or engagement in an activity.

3.

To emerge or appear in a noticeable or significant manner, indicating a change or response to external factors or conditions.

4.

To take a stand or position on issues, reflecting one's convictions or intentions, often in the context of advocacy or participation.

Example:

次々に立って出ていった。