This achievement can prove to be a little bit tricky in the beginning, but can turn out to be rather easy. You don’t have the ability until you level up more, so basically until you don’t unlock it until late your first play through or second play through. There are two ways that you can get this achievement. One way is in the chapter “School Invasion”. When you’re at the part where you have to raise the bridge by wall running up to two levers, don’t raise it. There’s a fire blocking off the rest of the passageway from you and four enemies will constantly respawn from there. Wait for the four of them to gather around near each other and then use a in focus horizontal attack to cut all for of them in half. Another way to do this is on your second play through on the “Prelude” chapter. When you get to the are where you have to fight a bunch of ronin and it tells you to go into over focus mode, don’t. Just run around until a bunch of ronin are bunched up together and then use a in focus horizontal attack to slice four of them in half.