Control two avatars at the same time with only one finger. It is all that simple. You hunt demon and collect the soul with lovely summoned pet. It sounds that the control will be complicated with 2 avatars but in fact only one finger is needed during the entire gameplay.
The control mimics the play of yo-yo that you just tap the summoned pet with the circle movement again and again on the screen to initiate attack and protect you from being hurt by those crude, wandering demon. While normal attack the most of the job, there are certain special attacks to assist; certain gestures will trigger special attack.
From battling with these evil demon, you will be more comfortable. The trick is that judging the position between two avatars will be essential. In the end, how much you can accomplish depends on the skill you have. Nevertheless, you will be a great soul collector.