How do you get to the door behind boss in Hamtaro Ham Ham heartbreak?

Answer 1

there are two doors. the first one is the rub-rub room to get to that you have to: buy oil from the sales lady in the cave at sunny peak; then right when you walk into the cave there is a lever/switch, you putput the oil on the lever and then you click it. you will hear something move and you go wear the train cart is and gogo in there, it will take you a different place than usual and two hamsters will teach you rub-rub. then you go back to the clubhouse and boss will move to another door.

to open that door you have to beat spat in spat tower. you beat the puzzle on the ground and talk to the sad hamster about his girlfriend. when you tell him that you will help him he moves. you go in to the tower and throw a rock with your slingshot into the robot's mouth. it doesn't work so you go tell harmony chuck-chuck and she gives you love-shots. you go back to spat and shoot a love-shot into it's mouth and it will explode. after spat fly away, harmony walks in. even though you still have to save the hamster and his girlfriend, you can go back to the clubhouse and boss will move and him and harmony are waiting at the door for you.

Answer 2

To unlock the door behind the boss in Hamtaro: Ham-Ham Heartbreak, first, you must defeat the boss and obtain the key item it drops. Once you have the key item, return to the door and use it to unlock and access the area behind the boss.