The opening cut-scene tells you all you need to know about Onechanbara: Bikini Samurai Squad. The title tells you all you need to know actually, but anyway. A bottom is having a shower. It's all rosy and rounded and pert, like two boiled eggs wrapped in a velvet handkerchief. Steam rises as the bottom sways gently under the cascading water. The aesthetic is only ruined by a dirty great tramp stamp, which is probably supposed to be the Celtic symbol for peace or serenity or dolphins but looks more like a Rorschach test for whether you're likely to kill dogs.
Cut to another room in the same apartment. A pre-pubescent girl in a school uniform is watching a news report about zombies. She shouts something to the bottom, which turns out to be attached to a hot chick. The Hot Chick races into the lounge, her modesty protected only by a pot plant in the foreground, where she pulls on a pair of microscopic pants and prepares for battle.
What would you equip yourself with in this situation? A kevlar vest, perhaps? Camouflage gear? A nice pair of sensible shoes? Don't be ridiculous. The most suitable attire for fighting an army of flesh-hungry mutants is a bikini, thigh-high boots, a feather boa and a cowboy hat. For everyone knows that zombies have no fear of military operatives, but are terrified of strippers and Venga Boys.