This is very time sensitive and must be prioritized. You must reach Hody before a certain time limit. After defeating Hody the first time, head to the first ! on the map, you will need to defeat a captain to open the door, after that destroy the second ! on the map, and then go to Hody to trigger the scene, but don't worry about fighting him now, you need to go clear Treasure Events 4 & 5, and build up more KOs for S rank.