There's ample reason this is a staple of the "Bought this on my trip to Japan!!!" genre.
Sure, the title of this review is a little reductive, but I think it does capture the surface appeal of Osu! Tatakae! Ouendan quite well. OTO is the first in a series of rhythm games which received a unique western entry, Elite Beat Agents, during the formative years of the Nintendo DS. It slots in neatly with other Japanese handheld games which have just enough of a language barrier to scare away those diametrically opposed to learning anything, but remains legible and simple enough to be eminently playable by the most novice students of nihongo. You could also brute force your way through the Japanese to get at the game inside here, or refer to the ample English language FAQ documentation to help you get started. Much like the other Ur-example of this import friendly class of games, Rhythm Tengoku for the GBA, you would be remiss in letting the language put you off. This is a friendly game!
As for the game, it's Elite Beat Agents. If you enjoyed that fantastic stylus-based rhythm game but were hoping for fewer Michael Jackson covers in your life, OTO has you covered. There's the seemingly mandatory period cover of "Linda Linda" here, but as a non-resident of the nation of Japan the majority of the music was new to me. I'm the sort of person who would play Elite Beat with an exclusively public domain soundtrack, so having what amounts to a level pack of curated tracks suits me fine. The game controls as well as ever, and the zany vignettes which frame the tracks manage to convey their story beats through exaggerated characters expressing "big emotions" ala The Room.
What's even better, you could effectively copy and paste this review for the Japanese-exclusive sequel, Moero! Nekketsu Rhythm Damashii Osu! Tatakae! Ouendan 2. Said title is the same game with a new thin plot, a new set of domestic tracks, and identical gameplay. The latter might explain why one of these games hasn't been made in over a decade now: there's not really anyplace to go once you've nailed your central concept so well from the drop. That does simplify things from the import perspective, however, as you know exactly what two titles to nab on eBay or during your trip to Okinawa if you want more of that Elite Beat Agents experience.
-4 out of 5 male cheerleaders performing a synchronized dance to "Linda Linda" to help a teenager pass their exams