When naming Isaac, press Select 3 times, and your will be able to name Garet, Ivan, and Mia.
If, when naming Mia, you press Up, Down, Up, Down, Left, Right, Left, Right, Up, Right, Down, Left, Up, and Select, you will be able to name Jenna, Felix, and Sheba.
Return to Last Sanctum:
In the Load Game screen, press and hold L, Start, and Select, then load the game. You will be in the most recently visited Sanctum.
Unlock Send Mode:
If you have a cleared file, when you are in the black menu screen, press and hold R and Left on the D-Pad, then press Start. The Send option will appear.
Secret Treasure Room:
In Lunpa, near Dodonpa's Fortress, there should be a boy and a rock. Use Reveal on the rock to turn it into a puddle, then freeze it. Climb up the nearby ladder and cross the pillar. Follow the path. Use Reveal and press A to go in the room and get all the chests.
*SPOILERS*
*SPOILERS*
