During an exam, the whole class is forced to duck as they hear a tapping noise, as they assume it's an earthquake. However, it's just Kenichi tapping one of his feet on the tiles. Furious that he scared them, Mr Koike tells Kenichi off for tapping his foot.
Back at home, Kenichi still can't stop tapping his foot, and eventually Hattori makes a sack which bears a whole ton inside it land on Kenichi every time he taps his foot. As Kenichi grimaces in pain, Kemumaki and Kagechiyo, who are watching on, laugh at him. Eventually, Kenichi tells Hattori that his plan really isn't working, so Hattori builds a machine which makes butterflies flutter about when Kenichi taps his foot. When Yumeko comes to visit Kenichi, he entertains her with the butterflies as they revise, but Kemumaki and Kagechiyo are spying on them.
Next day, during the Chemistry lesson, Kenichi is accused of tapping his foot when Kagechiyo uses a vibrator and makes a mess. Thankfully, Kenichi tells Hattori, who gives him a cowbell to tie to his foot. Kenichi then pops off to Yumeko's.
At Yumeko's, the gang make a jigsaw puzzle of The Wizard of Oz, but not before telling Kenichi not to tap his foot on the ground repeatedly. When Kenichi automatically starts doing so, he tells his foot to relax and sits down on it. Just then, Kagechiyo turns on the vibrator and Kenichi wobbles like an earthquake. Hattori then sneaks in and ties a giant cowbell onto Kemumaki's waist. Kagechiyo, assuming that that's where Kenichi is, goes to Kemumaki and wobbles him about, and the blame is placed on Kemumaki. That night, Hattori uses the Ninja Technique of foot-tapping to get himself some beef rolls.