You also play memory - the game where you flip cards over and memorise their location so you can make pairs. After five minutes of each, you're locked out of the game until the following day.
The more days you log into the game, the more exercises you unlock.
There are also brain-training activities focused on problem-solving and puzzles, as well as a match-three game - think Bejeweled - designed to give your brain a rest between tasks.
All of these activities are fun and can get difficult quickly. Whether they're effective or not is a different question. The more you play a game, the better you'll be at it, and I got better over time. However, the scientific consensus is that brain training doesn't have any real impact.
Dr Kawashima's Devilish Brain Training seems like a good way to spend a few minutes, but as for improving overall concentration ... well, I'm not holding my breath.
I should probably just stop checking my emails in meetings instead.
Dr Kawashima's Devilish Brain Training
Platform: Nintendo 3DS
Rating: G
Verdict: Devilishly difficult, but just a game