The Apachai Flashback Arc is the ninth arc in the Kenichi: History's Mightiest Discple manga series. It was omitted in the anime, but consist of chapters 106-109 in the manga.
Kenichi was doing Miu's chores as an apology for forgetting to tell her that Ryozanpaku would keep the cat. Kenichi then found out that Hayato bought an ink painting that was really expensive. He wanted to tell Miu, but the elder proposed to tell Kenichi how he met Apachai, also telling him that there's a reason behind the inking that's related to that, so he wouldn't tell. Back when Miu was a child, Hayato and Miu came to a dying village that has no children. When the villagers recognized Hayoto,they paid him with what little they could get to stop drugs and weapons smugglers that took their children and other things from the villagers. Hayato refused the money, but took the job anyway. The villagers warned the elder that the smugglers have a certain man called Apachai Hopachai working under them. The two saved a child from some thugs. While Miu was resting to have lunch, she saw Apachia (though didn't see who he was with a cloak he has on). She shared a rice ball with him and saw him being kind to some animals. The elder got to the ship by running across the water with defeated a lot of smigglers until he met Apachai. While Hayato fought Apachi (While was breaking the ship), Miu-who snook into the ship secretly- was looking for the missing children only to be captured as well. When it looked like Apachai was going lose, the smugglers were shooting at Hayato from all direrctions (even directions that would hit Apachai as well). The elder found out that Apachai was working for the smugglers, because they fed him some food by the boss when he was starving and thought they were taking the children to a amusement park. Apachai then realized they were lying and helped the elder, but the elder used Shockwave Forgetfulness Technique to erase the smugglers' boss memories. Four days later, the children were returned to the village and gave them the smuggler's treasure that they salvaged. The elder did take the money the villager's money that was offered to them, because of their gratitude. Before leaving, the elder gave the villagers info on whom to get for protection from further threats. Apachai them followed Hayato and Miu all the way from Thailand to Ryozanpaku and was welcomed there. Back to the present, Kenichi was about to tell Miu anout the saving spent, but Hayato used the same Technique to make Kenichi forget about the elder's spending. Kenichi continued to do Miu's chores for at least one more day.
- Apachai's past and how he met the Elder is shown.