Meccha! Taiko no Tatsujin DS: 7-tsu no Shima no Daibouken Cheats - Nintendo 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 Options
Play songs in the standard mode:

Abekobe Option - Pass 30 songs on Kantan (Easy) difficulty
Doron Option - Pass 30 songs on Futsuu (Normal) difficulty
Kanpeki Option - ass 30 songs on Oni (Demon) difficulty
Yonbai Option - Pass 30 songs on Muzukashii (Hard) difficulty

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
Most songs are unlocked by defeating the boss stage in the Dojo Yaburi minigame:

Classic Medley (Classic) - Reach 5000 Taiko Counter
Dragon Spirit Medley (Game Music) - Reach 50000 Taiko Counter
EkiBEN2000 (Namco Original) - Defeat boss in Meka Island
GO GO Kitchen (Namco Original) - Defeat boss in Otome Island
Hyakkaryouran (Namco Original) - Reach 10000 Taiko Counter
Numujika ac.10 (Namco Original) - Reach 99999 Taiko Counter
Rhapsody In Blue (Classic) - Defeat boss in Ryuuguu Island
Ridge Racer (Game Music) - Defeat boss in Nyan Nyan Island
Saitama 2000 (Namco Original) - Defeat boss in Omen Island
Taiko Samurai (Namco Original) - Defeat boss in Taiko Island
Warera Muteki no Dokon Dan (Namco Original) - Defeat boss in Dragon Island
Yami no Tamashii (Namco Original) - Defeat final boss in Dragon Fortress

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