Ron is trying to teach his little sister Hana the basic toddler things, but it proves much tougher than he can handle. While on the phone, Kim warns him NOT to let her out of his sight, but after a few moments the living room is in chaos, including hand and footprints on the ceiling. Ron worries he can't handle Hana well enough, but Kim encourages him not to give up. At first Kim doesn't believe Hana walking on the ceiling, but when she offers to help Ron babysit Hana, he proves her right - Hana bounces off the ceiling, tramples along the furniture, and destroys the whole living room which luckily they manage to clean up before Ron's parents show up. Meanwhile Monkeyfist is sulkily trying to grapple the fact that he has been defeated by "a mere infant" (Hana) while searching for second half of a scroll revealing the location of the temple of "Yono the destroyer", which he believes will help him seek the "weapon" for power. After Kim and Ron deal with Hana's unbelievable energy, Kim becomes curious as to who handled Hana's adoption, however, they are shortly interrupted by Ron's parents and Wade, who tells them that Monkeyfist is trying to steal the second part of the scroll at a Museum. Kim and Ron rush to the scene, only to find that the ninja monkeys are hurling priceless items at the floor to break them.
Monkey fist dusts the scroll and escapes, leaving a frustrated Ron and Kim to head home, luckily, Wade manages to access a copy of the scroll. While home, the couple decides to trace Hana's adoption agency, leading to a Pet store and a Punk rocker girl who tells them the Adoption agency doesn't exist anymore, but promptly shows them junkmail sent to the has-been agency. They find out the adoption agency was called "Yamanouchi Adoption Agency" and find out that Sensei had placed Hana into Ron's family to prepare her for a showdown with the Yono.
Monkeyfist unearths the temple of the Yono, and decides to give up everything to follow the path of the Yono. While the Yono marches to school (probably indicating that he had once been educated there) Ron almost breaks down at knowing the fact he had left his baby sister unprepared and vulnerable to being killed by the destroyer. Sensei encourages him to take a while alone with Hana, and he leaves with Hana, unaware that Monkeyfist and his Ally have reached the school and are preparing to destroy it. Sensei notes that the time has come for the showdown, while Ron is down by the springs with Hana, where he discovers that his sister was "secretly" learning everything already. Back at the ninja academy, Kim, Sensei, Yori, and Rufus are anticipating the arrival of the Yono. The Yono arrives and Kim provokes Monkeyfist, eventually making Monkeyfist realize that the weapon - "Han" was actually Hana, Ron's baby sister. Kim and Yori, but the Yono effortlessly tosses them away, and petrifies (or stonefies) Rufus, Sensei and Kim, leaving Yori to warn Ron. When Ron arrives, he sees the temple of the Yono, and Kim's petrified statue and gets furious at Monkeyfist, but Yono nearly petrifies him, and the Ninja monkeys bind him together in ropes, leaving Hana to the final showdown.
The Yono tries to destroy Hana, but due to Ron's video cassette coming out of his pockets (due to him trying to shake off the monkeys) Hana dances and jumpes around effortlessly, avoiding the "flash" (as the Yono calls it). After Hana lands on Monkeyfists face and knocks him down unconscious, the Yono accepts his defeat, and agrees to stop to teach Monkeyfist the path of the Yono, reversing the petrification. Kim and Ron briefly kiss (they were interrupted by Hana as well) and as Kim asks "Where's Monkeyfist?" Ron points out that Monkeyfist has been petrified and seemingly made a "pupil" (or Guardian) of the Yono. The episode ends with Han running around the ceiling again.
- Second kiss of Kim and Ron but was interrupted by Hana.
- 81st episode in chronological order.
- 82nd episode in production order.
- In this episode, the running gag this season where someone interrupts Kim and Ron kissing continues on. We finally get to see them kiss, but it was brief due to Hana jumping between them.
- Although Ron accidentally jumped into the spring, dodging a rock Hana had sent flying, his hair mysteriously dries up at night while entering the school.
- When Ron gets tied up by the ninja monkeys, in the next scene the ropes are gone and he is being forcefully held by the monkeys.
- In Big Bother, it was the Middleton Adoption Agency, but in this episode, it was the Yamanuchi Adoption Agency.
- The position Kim was in when she was becoming a statue was different than the one that was made when she became a statue even though the effects were shown to be instantaneous.
- The scrapbook Monkey Fist looks through, the keys and shrines he talks about and the flashback to when he was defeated by Hana are from "Big Bother", the previous episode Monkey Fist was seen in.
- Sensei uses the same line "this is my way of telling you" that Ron's parents used on him in the A Sitch in Time and "Big Bother".
- In the credits, Ron says to his parents that not saying anything was his way of telling them about Hana's secrets. This is Ron's way to get back at them for using that line on him.
- The Flippies, the show that Ron and Hana are seen watching in this episode, is based on the popular children's show, The Wiggles.