When you reach the end of chapter 6-4 you will encounter a boss: Evil Butcher, he has 2 phases, when his HP is reduced to around 5% he enters phase 2, and the game auto-saves checkpoint. During phase 2 he will put a cauldron on his head, he will be invincible against anything but aerial attacks. A single aerial attack (A→X, A→Y, just anything aerial) will stun him and you can initiate a QTE scene by grabbing (RT). Successfully completing button smashing QTE will kill the boss and award you 1000 EXP. DO NOT pick up the key he drops (Picking up the key will overwrite checkpoint save), open menu and select Restart from Last Checkpoint, you will restart from the beginning of phase 2. Repeat phase 2 for easy EXP.

6-4屠夫Boss，先正常打，打到它还剩大概5%左右的HP的时候会进入P2，这里有一个检查点游戏自动存档。Boss会在头上戴一个锅，此时除了头部全身无敌。跳起来（A）砍一下（X或者Y都行）Boss就晕了，晕了Boss的刀会高亮，直接抓取（RT）进入一段小动画。动画中间有一个按键连打的QTE，QTE搞完播片播完Boss就死了，给1000经验值。Boss掉落的钥匙一定不要捡（捡了就覆盖检查点了），直接开菜单点从上一个存档点重来，就会回到P2刚开始。重复P2，一次不到一分钟，1000经验无脑刷就行了，甚至可以在这里直接买齐各种连招和强化。

In summary: reach 6-4 boss phase 2, A→Y, RT, do the QTE, get 1k EXP, Restart from Last Checkpoint, rinse and repeat.

简单来说就是，在屠夫Boss的P2，跳跃攻击(A→Y），抓取（RT），QTE，1000经验到手，从上一个存档点重开，循环速刷。

You will need around 110k+ EXP to purchase everything in the game.

买齐游戏里所有的东西（连招，强化，画廊）大概是11万多经验值。