In the Persona 2 duology, certain personas are restricted and require a special item before they can be summoned; this item is called a Material Card. Material Cards can be obtained through different methods: they can be found in chests inside of dungeons (Iris' Rainbow Light), be dropped by certain rare enemies (Izanami's Netherworld Path), can be purchased using coins at Mu Continent (Satan's Prosecutor's Diary) or acquired via Mystic Change (Lucifer's Morning Star). Some can only be acquired once, while others can be acquired multiple times. However, all Material Cards are consumed upon use.
Talk to the Wang Long-obsessed girl in Double Slash in Aoba; for birth month, say "HASTURCOMEFORTH" In the Japanese version, it is (イアイアハスタア), afterwards the card will be found by Maya's desk in Kismet Publishing.