After you have raised the main 15 islands, Wada will inform you, Agete, and the Harvest Goddess that Sunny Island has suddenly sunk to the bottom of the ocean! The Harvest Goddess explains that the same problem that affected the previous islands have now impacted Sunny Island, but she can stop the sinking from happening again. The goddess needs you to locate the remaining 30 Sun Stones and raise Sunny Island off of the ocean floor.
Sunny Island does not appear on the top-screen map! You can only use the boat from your farm to reach it. The teleport stone can not transport you there. Sunny Island is the jungle area that eventually becomes the same Sunny Island in Island of Happiness.
Previously, Wada lived on Sunny Island and spent Wednesdays and Thursdays on Mushroom Island. Until you collect the necessary Sun Stones to fix his home, Wada will move into Shea's tent and spend every day of the week there. If you are planning on marrying Shea, make sure you see his Blue Heart event before Sunny Island sinks. When Wada lives inside Shea's tent, you can't see the Blue Heart event.
After you raise Sunny Island, you can visit by using the boat dock on Ranch Island. Sunny Island has unique fish to catch, but no wild herbs to collect.
Sunny Island's main benefit comes from Wada. If you do not talk to him at all until he is inside his house between 10:00 am and 3:00 pm, you can get a random food item from him.
Wada will give you anything edible, whether it is a cooked recipe or a crop. He can even give you crops that you may not have unlocked yet! This is handy for getting cooked recipes from Nick and Haila, or completing your shipped items list. If you own the Seed Maker, you could even take that crop and convert it into seeds for growing.
Save your game before talking to Wada and if he gives you an item you don't want, simply reload your saved game and talk to him again to get something different.
Wada's daily gift is very much like the Wada's Friendship event from Island of Happiness, where you can get a random gift from Manfred every day.
Hidden Sun Stones
There aren't any Sun Stones on Sunny Island! If you have raised Sunny Island, then you have collected all 100 Sun Stones. Congratulation!