Yukkuri as Reactive armor? Yukkuri fail horribly at that! Especially since Reactive armor actually negates part of the damage by exploding when the enemy round impacts it, and there a significant lack of yukkuri that explode from strong impacts. (Excepting Utsuhou's, but those probably disperse radiation when they explode, so that's a no go either.)
Yukkuri as Ablative armor, on the other hand......would still suck, but they would do a better job at being ablative armor then they would as 'reactive' armor. XP
Yu... actually, I like the Reimu at the front...Marisa, you are not easy today. What happened on you?Probably nothing would happen on that customer...?Ayaya...after this war, I'll marry her...Finally I've decided,Remember to appoint a commanding officer, avoiding any unnecessary trouble...?Instruction: Open the ventilation valve. Wake when exposed to room temperature.Have you seen it? Quickly tell me!