Here is the full list of all 10 Mr. Saitou achievements.
Get through the day at Saitou Corp.
Push Subpartou's button 50 times.
Witness the Minimori Migration at SaitouMart.
Speak with Undefined, Sphinx of Math until he tells you everything.
Place a Minimori on every pedestal in the Ancient Minimori Meeting Ground.
Talk to all the plants. Even the one with.............. problems.
Go to a "No Holds Bard!!!" concert.
Visit the Flooded Gemstone Caverns with Brandon.
Pick up snacks for the train ride home.
Complete the game.