How to get into the tower on the island?

Are you talking about the fc Chinese version of 7? That's dq4. You're talking about an island on a hot air balloon. The tower on the island is called Sky Tower, which leads to Sky City. You need to collect a whole set of sky equipment to get in, otherwise it will bounce off.

Helmet in Stanchard, Panon was rewarded for telling jokes to the king. The armor is in the cave below the metal king city, the shield is in the plot of Gartenberg's little secret cross, and the sword is at the top of the world tree (that is, the place marked with X on the map).

In addition, after climbing to the top of the tower, you should also equip yourself with a full set of sky for the clouds to pick you up.