The new wave of mobile collectible card games — which I still do not understand — is really starting to branch out. For awhile there it was all collectible fantasy creatures and demons. Now Aeria Mobile swaps collectible creatures for collectible women. It's okay, they're pirates.
30°
40°
40°
40°
Ad 
40°
If you want a good free-to-play card game, try Square-Enix guardian cross. Every 5 days you get a chance to win an x-amount of rare cards ranging from 3-5* (through special hunting tickets), or you can win special hunting tickets in the tournaments (2x if you place in C or higher). Also the cards have actual moves with animation, instead of a freaking flash and then a winner announced. Also Square-Enix doesn't over-charge, compared to other card games. Also strategy is involved as you have to pick your cards moves and make sure they are appropriate to your card. For example if you have a card thats physical give it physical moves and find the card type of that card thats "powerful" cause itll boost his physical abilities.
In the other card games, everything is picked for you (skills, who you fight with in your deck, card type etc). You dont do crap, all you do is press a button, theres no player involvement. Trust me, don't waste your time. Also if you gonna download ayakashi or pirate maiden for the "sexy anime girls" you'll be disappointed, as the cards you get free aren't as "sexy" as the ones you have to pay for, nor as strong.
One last thing. EVERY card in Square-Enix game can be caught free-of-charge. Doesn't matter if very common or very rare. In ayakashi and this game, only weak cards can be caught the strong and higher stars has to be bought or be ready to spend A LOT of money or time hoping you get extremely lucky.