Move along the next room. In the room with a Mars Djinni and an ice block, stand in front of the ice block and use Grind. It will drop to the floor below and make a crack on the massive ice block. Now go all the way back to floor 1.

Click here and see the map of Floor 2

In floor 2, follow the corridor into a room with a Mars Djinni. This is just another easy battle. After you defeat it, you will get the Mars Djinni Fugue. Use Retreat to leave the Mars Lighthouse. It's side quest time!