I believe theres plenty of guide on how to find these costume so ill wont keep it long here.
Basically, you can get Lingerie at level 7 boss fight, Bikini Armor at level 8 cave area, Reverse bunny at level 8 hospital area with 3 buttons that was scatter around randomly each time and you need to find it, Combat Armor at level 8 factory area with some parkour to do, all area is after checkpoint. For level 8 the problem is that after checkpoint it will only open 1 door to 1 area which mean you can only get 1 costume each round you load in, so sometime you will just reload the map over and over just to get the right door.
P/S：The body size of the character have been changed, please dont mind.

怎么获取就不多说了，有很多攻略了。 那就长话短说，情趣内衣第七关boss房，比基尼铠甲第八关洞穴，逆兔女郎第八关医院找3个随机分布按钮，战斗服第八关工厂跑酷。第八关每次载入只会开一个区域所以每次只能刷一种服装，可能要一直重复载入来开到要的门。
P/S:女主角体型有改动，请别在意。

Lingerie/情趣内衣


Reverse Bunny/逆兔女郎


Bikini Armor/比基尼铠甲


Combat Armor/战斗服

Lingerie/情趣内衣


Reverse Bunny/逆兔女郎


Bikini Armor/比基尼铠甲


Combat Armor/战斗服

Lingerie/情趣内衣


Reverse Bunny/逆兔女郎


Bikini Armor/比基尼铠甲


Combat Armor/战斗服

Lingerie/情趣内衣


Reverse Bunny/逆兔女郎


Bikini Armor/比基尼铠甲


Combat Armor/战斗服

If theres any problem feel free to sound out. Although some people are asking for save files with complete costume but I have no idea how to do it. And thanks for reading until here, hope this guide is able to help you.

如果有什么问题请尽管开口。虽然有人求有完整服装的存档但我不懂怎么弄。谢谢看到这里，希望这篇文能帮助到。