All Working Forbidden Siren Cheats - Playstation 2

Time attack mode
Successfully complete the first two objectives on all levels in every scenario (78 blocks filled on link navigator) to unlock the first ending sequence. Then, press [Square] at the scenario selection screen.

Brain Cell Revival (Zuno) puzzle mini-game
During Tamon Takeuchi's Day 3 03:00 level, a Brain Cell Revival mini-game can be found in a child's grave when you switch over to Kyoya Suda. Successfully complete the level and save the game. An option to play a new puzzle game will now appear at the main menu.

Mission Objectives 2
To unlock Mission Objectives 2 for every character and/or scenario, complete 19 stages in any order. Then, press [L1] + [R1] while the stage is highlighted at the scenario selection screen. Note: You will automatically obtain it after completing the random 19 stages.