with all the study methods you have to pay for, this specifc study app is not only entirely free, but is one of the best tools I've been able to add to my studying tools. As someone who has jumped from study app to study app, this app has done wonders for my memorization of key components of japanese. NOTE: I'd still reccomend using other methods alongside this one, but don't underestimate this app, its heavily effective if used properly.