All Working Meccha! Taiko no Tatsujin DS: 7-tsu no Shima no Daibouken Cheats - DS

Oni Mode
Beat 35 songs in Muzukashii mode.

Unlock New song
After hitting the drum for 5000 times total, you unlock a new song, called "Classical Medley (Rock ver.)"

Unlock Notes
Most of these unlocks are performed through the Dojo Yaburi mini-game.

Dora - Dragon Island completion
Gong - Reach 6-Dan in Mainichi Udedameshi Dojo mode
Kendou - Omen Island completion
Kuizu - Reach 10-Dan in Mainichi Udedameshi Dojo mode
Mokugyo - Taiko Island completion
Onara - Reach 3-Kyu in Mainichi Udedameshi Dojo mode
Pucchin - Meka Island completion
Suzu - Nyan Nyan Island completion
Tsudzumi - Ryuuguu Island completion
Wata Don - Reach 9-Kyu in Mainichi Udedameshi Dojo mode

Unlock Songs and costumes
Play any mode to accumulate Taiko Counter, or beat adventure mode:

Abekobe mode - Beat 30 songs on Easy
Doron mode - Beat 30 songs on Normal
Dragon Spirits Medly song - Reach 50,000 Taiko Counter
Hyaka Ryoran (White Flower) song - Reach 10,000 Taiko Counter
Kabuto (Samurai Helmet) costume - Beat Adventure Mode on Sweet difficulty
Kanpeki (Perfect) mode - Beat 30 songs on Oni
Kare Kano Canon song - Reach 30,000 Taiko Counter
Numujika ac. 10 - Reach 99,999 Taiko Counter
x4 mode - Beat 30 songs on Hard
Yoroi (Samurai Armor) costume - Beat Adventure Mode on Hot difficulty