Streetpass

Streetpass is one of the secondary functions of the Nintendo 3DS. It allows data to be shared between players' 3DS systems, and is used by some games for additional features. Streetpass only works for games in which both players have enabled it.

Shin Megami Tensei IV
Before Flynn reaches Tokyo, Burroughs will activate the Streetpass function. There are 2 different versions: White Card, and Black Card. White Cards allow the player to obtain items, while Black Cards allow the attached demon to change into another demon with an additional skill. There is also an update patch on the 3DS E-Shop which allows players to gain 40 App Points for a successful streetpass when both players have SMT4 and either Soul Hackers or Etrian Oddysey 4.

Devil Summoner: Soul Hackers
In the 3DS remake of Soul Hackers, the special demon Nemechi can gain D-Souls using the streetpass feature, which are used to purchase new, special demons added to the remake.