Japan Sinks (ニッポンチンボツ, Nippon Chinbotsu) is the ninth episode in Japan Sinks: 2020.
Releasing their mothers body into the sea, Go and Ayumu says their farewell with her and head towards Onodera's coordinates. They see a flipped boat and lots of food supplies floating around and take some. Their motorboat engine eventually stops and Haruo plans on diving to check it out, but see a military amphibious vehicle approaching them. Kite comes out of it and explains that Onodera is with him and tells them to get in. They reach a lighthouse and decide to take a break there. As a hot spring erupts, they decide to take a bath and enjoy it. Go comments that he hates Japan and that if they weren't here, their parents won't have died. Kite puts some music and starts rapping, wanting to cheer them and tells Go to let his frustrations. As Go goes, he turns to Haruo and tells him to defend Japan, and after Haruo, Kite turns to Ayumu who also raps. Kite then turns to Onodera if he wants to rap too and Onodera using Morse code says that he will punch all those who mocked him. Ayumu then proposes they take a picture together and they gather around Onodera and take a picture.
The group decides to continue to Onodera's coordinates, where Kite comments its the last place in Japan that can withstand natural disaster. If they can combine the latest data Onodera saved in the cloud with the archives, they may get important information that could save Japan. Reaching the coordinates, Kite sees a cave and figures the secret base is at the end of a cave. He leaves the rest and takes Onodera and tells them, he will return before the big upcoming earthquake. Kite enters the secret base and takes out one of Onodera's teeth that has a hidden USB drive. While he transfers data from it, an earthquake occurs causing the cave to be flooded. As the power goes off, he takes the hard drive, Onodera and one tank of oxygen and tries to swim out of the cave. He switches the oxygen between him and Onodera until he is out, but then realizes Onodera isn't breathing and Go notices a hole in the tank, making Kite realize Onodera wasn't able to breath in the end and drowned. He tries to bring him back to life and eventually makes him caught the water, but a wave hits them and takes away the hard drive. The see the hard drive stuck, but as other waves come in, they count to figure the frequency of the waves and Haruo decide he would be able to go get it and get back.
Kite tells him this isn't like track and field running, but Haruo assures him he can do it. As he goes, Haruo reaches and takes the drive and starts running back. Getting close, he throws the drive at Ayumu, who catches it and then a big wave hits them and takes Haruo away. Kite starts yelling at Haruo, but they are unable to see where he went.