Long bow is another firearm of Jin Sakai’s. And in this guy, I’ll tell you where to find it.
To get a long bow, you’ll have to take your mind off the game and do one of Yamato’s quests. They’re all called Stories of Ancient Heroes. In one of them, you can find a long bow. You can learn about the musician from civilians in villages, towns or refugee camps. Just look for someone to talk to, and never miss an opportunity. As far as I remember, you can only take the Long Onion task in the second act when you find yourself in the central region of Tsushima.
A SHORT AND LONG BOW IS THE ONLY FIREARM IN THE GAME. YOU WILL NOT BE ABLE TO USE, FOR EXAMPLE, GUNS THAT SHOOT HEAVY OPPONENTS IN THE THIRD ACT.
On the other hand, there will be an alternative in the form of bombs, velcro, darts, poisoning enemies or pissing them off.