Course · 20 days
Numbers, properly.
Japanese groups digits in fours rather than threes. 90,000 is 9 万, nine ten-thousands, and a million is 100 万. That one difference, plus counters, is what trips learners up at a till, and it gets twenty days of its own here.
By the end you can handle a price, a timetable, a rent quoted in 万, a discount sign, a population figure and a road trip of 123 km.
A day is marked done when you pass its quiz at the end: get 5 of its 8 questions right. Miss it and you can take the quiz again straight away.