I probably forgot, but was there a point in time where Eita learned of the Marishiten's capabilities? It's also bit weird that neither UN nor NIN collected the armor in the first place.
Eita saw it partially on ch 37, p 17. When Kuro made him hit the bullies. Then on ch 43, when they discuss going to the Yankee school, Kuro mentions that he will be going invisible. So, he could've figured it out.
Also, it isn't so weird they didn't collect it. UN has better capabilities and they just don't care, escpecially Yamada. NIN didn't have time to care since they imploded.
But it is odd... Yamada cut the connection from the 9V during the fight. Severing the hoodies invisibility function.
Did he fix the hoodie and bleach the blood? What did he do with Kuros corpse and why did he?...
The implications just make Eita more of a skeever to me...
I hope we can see a flashback of how he got it.