There, you need to head to the dance theatre where you must defeat all five Kimono Girls. Once you meet them they will each challenge you to a battle and in order to get the reward at the end, you must defeat them all. The battles must also all be won in succession so you will need to beat the five Kimono Girls one after the other in order to be successful. Once you have completed this, you will then get the Tidal Bell.
Sometimes it can be a little confusing reading instructions and it may be easier to see how to win the Tidal Bell in a video. There are also some video tutorials available to view online that will show you how to get the Tidal Bell. Some of these can be viewed by clicking on the following links: