The kanji is the same as Guy's because that's the name of their fighting style.
Other than that, there's nothing that prevents Strider from being the same universe as SF, it wouldn't be a big reveal, so why not.
If I struggled to the end of my determination, to the end of my way of life with my followers, if the result is ruin, then this ruin is inevitable. Grieve. Shed tears. But you cannot regret.