Hereafter
After, Since
noun
Everything that happened since you descended some stairs, is hereafter. It's all after the stairs thing you did, since you did it already.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
返事は来週以降になります。
The answer will be next week or after.
八月三日以降にもう一度ご連絡していただけますか？
Could you call us again on or after August third?
夜九時以降の外出は父に禁止されているんです。
My dad forbids me from going out after 9 p.m.