Some DLC is not added to the european store because reasons. Seems to be especially bad with japanese games.

Try creating a new account where you state the US as your home and then you should get access to the US Store where you should then be able to download it for your game.

Try making a new account with US as your location. Although you'll lose your progress and have to basically restart on that account, if you really want that outfit on than go for it.

Nah that is too annoying, but thank you guys very much.=D
I rather stay without that outfit then.

It's still possible that the dlc will show up. Typically things like dlc or games get released in the US first and then take a couple of weeks to come out in europe.

I see, thank you so much.=D