1
(when) danger threatens;should an emergency occur
1
high and low speed;fast and slow;pace;tempo
2
lenience and severity
3
emergency;crisis;dire situation
いつもお世話になっていますから、一旦緩急あれば、すぐさま馳せ参じます。
You're always there for me, so if you're ever in dire straits, just let me know and I'll come running.