いこう以降ikou
1.
Indicates a period of time starting from a specified point and continuing indefinitely into the future, emphasizing the entirety of the time that follows.
2.
Refers to an ongoing situation or condition that begins at a certain time and affects all subsequent moments from that point onward.
3.
Used to highlight that a specific event or rule applies from a defined moment forward, incorporating that moment as part of the timeframe.
4.
Conveys the sense of something that will persist or be relevant starting from a certain date or time and onward.
Example:
それ以降彼は辛い一生を送った。