After lifting the curse from Nathaniel/Kenny's friends, you are able to defeat Kin and Gin with Nathaniel/Kenny's help.
Jibanyan Comes Home
After Jibanyan storms off, talk to Whisper, then go outside. On the way, you can talk to your Mom to start another Key Quest at the same time.
Outside, go west and talk to Komasan to find out that Jibanyan went past the bakery. Then go to the bakery and talk to Noko to find out that Jibanyan went to the river. Then go northwest to the river and go toward the schoolgirls.
After a cut scene, go downstairs and watch another cut scene. Then the next day, go downstairs and talk to Amy. Say "Meow" to join her. Then the next day, do the same thing.
After the cut scene, the quest is complete.
Retrace Dad's Steps
Talk to your Mom to start this quest. Then go to Sunshine Station in Blossom Heights and buy a Day Pass. Go to the right, and the station attendant will tell you to check Spring Station. You can get on the train here, or just go outside and warp to Springdale Central Station. Then take the Central Line train from there to Spring Station.
Talk to the station attendant at Spring Station, who tells you to check Fortune Place. Afterward, you can talk to him to start the All Aboard stamp rally quest. Take a train back to Springdale Central Station, get off and take the Central Line Express train to Fortune Place, or take the Central Line to San Fantastico and get off at Fortune Place.
Talk to the station attendant at Fortune Place. At that point you realize that your Dad might not have left the envelope on the train at all. You can get on the Central Line Express to Springdale Station, or you can take the local train to Spring Station and get off at Springdale Central Station.
Go outside and go southwest to your Dad's office building. Take the elevator up to the 7th floor. Talk to your Dad, who is standing near the elevators. Whisper recommends befriending Flushback. He can be found in San Fantastico.
Flushback's favorite food is Soba, which is hard to find. Look for the soba delivery guy riding his bike around Uptown Springdale, Shopper's Row, or San Fantastico when the weather is clear. Follow him and he will eventually drop some soba. Then you can warp somewhere else with Mirapo and warp back to where you found the soba guy, and follow him again to get another soba. You can keep doing this to get as much soba as you need.
Flushback is a Rank D Yo-kai. In San Fantastico, you can find a Hidden Workshop in the southwest area. Flushback often appears there.
After you befriend Flushback, go back to the Office building in Downtown Springdale and take the elevator to floor 7F, and talk to your Dad. He will say that he went to the Piggleston Bank, the Bike Shop, and then from Sunshine Station to Springdale Central Station. From there, he went to Nom Burger.
Go to the Bike Shop first. It's in Blossom Heights, south of Timers & More. Talk to the bike shop owner, who is standing outside.
After you get the envelope, go back to the Office Building and talk to your Dad.
Now you can choose a bicycle. There are five models to choose from. You can change it afterward, but not for free. You can also change the bell sound. The more you ride the bike, the more color customizations you unlock.
Go for Rank B!
One of the Key Quests to complete is to upgrade your watch to Rank B. Talk to Mr. Goodsight at Timers & More. He will tell you to defeat three Yo-kai in San Fantastico.
Go to the Hidden Workshop in southwest San Fantastico and talk to the Chummer near the entrance who has a blue flag over his head.
Then go to the cave where you found Mermaidyn, and go northwest to find the Chansin that has a blue flag over his head.
Then go back to the Eyepo near the cave entrance, and go west from there to find the Ben Tover with the blue flag over his head.
After you have defeated all three, go back to Timers & More and talk to Mr. Goodsight.
This Is a Yo-kai Storm?
After you complete the Key Quests, go back home. There will be a cut scene. After the scene, go outside.
Go to Brokenbrella, who is standing near the Everymart. There will be Yo-kai along the way, and if you touch them you will have to fight them.
Next, follow Brokenbrella southwest of Everymart.
After that, go north to find Brokenbrella again.
Then go west to reach the Yo-kai that is causing the typhoon.
Target each of Eyeclone's hands until they shatter. Then target his remaining eye.
After you defeat Eyeclone, you befriend Brokenbrella, and the chapter ends, starting the next chapter, Big Yo-Kai Battle.