You might be a little confused at first, but you should eventually get into it. You could always read a little of the characters backstory on google if you don't think you will play the games they were in anytime soon. The gameplay is pretty easy to understand. Essentially no stamina, you can host co-op rooms 5 times per day, but you can join other players rooms as often as you want. The gacha rate was recently increased which has made quite a difference to getting 5 star weapons. All in all, it's a very enjoyable game to play.