Do you want to get a bit of Shining Hearts in your Valkyria Chronicles 3? Then visit the EXTRA -> PASSWORD menu in Valkyria 3 and input the following password:

P 9 F M E B 2 A 5 Q 9 G N F P W

This password will unlock a sticker that shows Neris, one of Shining Hearts' heroines:

The sticker, called "Itasensha," or "Itatank" (like "Itasha"), dresses your tank up like so:

You can select it from the briefing menu.