Ikkaku Madarame vs. Tetsuzaemon Iba

Ikkaku Madarame vs. Tetsuzaemon Iba was one of the battles that occurred during the Ryoka Invasion. As the 11th Division captain and its members assisted the Ryoka and were searching for Ichigo Kurosaki, Yumichika Ayasegawa and Kenpachi Zaraki sensed an ominous presence indicating that there was someone hiding nearby. Kenpachi calls them out. Captains Sajin Komamura and Kaname Tōsen show themselves along with their respective lieutenants Tetsuzaemon Iba and Shūhei Hisagi.

The others in Kenpachi’s group are surprised to see them as Tōsen asks why Kenpachi is aiding the Ryoka. Yumichika mentions to Makizō Aramaki that they have them outnumbered for a fight, but Kenpachi states that he will be the only one fighting by taking them on 4 vs 1. Komamura and Tōsen both comment that Kenpachi is much too prideful while Kenpachi insists that they all come at him at once. As the rest of the group wonders what to do, Yachiru tells Kenpachi that the rest of them will continue on as he fights. As Kenpachi says he’ll catch up to them, Tōsen remarks that he can’t be serious, and that he must have lost his pride and his sanity. Kenpachi simply replies that he never had any sanity to begin with. While the group runs ahead, both Hisagi and Iba step forward and offer to fight Kenpachi first. As Kenpachi grumbles about how his opponents were looking down on him by not coming at him all at once, Ikkaku Madarame and Yumichika Ayasegawa step in. Kenpachi asks the two why they did not leave with the others, only to be ignored as Ikkaku yells at the lieutenants that they are not good enough to fight their captain as he and Yumichika would be sufficient opponents. Seeing that his two officers wanted to fight as well, Kenpachi lets them have Hisagi and Iba as opponents. Ikkaku is called out by Iba, who details that it has been some time since they last saw each other and how much more a loud mouth Ikkaku has become. Ikkaku retorts that he is the one to talk, making note that Iba left the 11th Division because he couldn't become lieutenant. Ikkaku then motions for them to move to another location so as to avoid being injured by Kenpachi. All four of them them leave

Battle
The battle between Ikkaku and Iba is not shown. It is presumed that they did battle as not only are they both later seen resting and having some discussion over their fight, but they both have their respective Zanpakutō's Shikai next to themselves.

Aftermath
Both combatants are seen resting and drinking sake with each other. Ikkaku comments about a lighting strike, saying that it would have hit them if they had raised their Zanpakutō up when it occurred. Iba scolds him for being ignorant as it was actually Kidō and not a lightning strike; so it wouldn't have reached them due to being a targeted attack. Iba then states that Ikkaku has not improved one bit as he still knows nothing of Kidō. Ikkaku tells Iba he was never interested in Kidō anyway and states that unlike him, his mother didn't make him a "do-it-all" type of guy. Iba explains that he wasn't always like that, but because his goal was to reach lieutenant rank, being well rounded instead of focusing on only one skill meant a better chance at a promotion to that rank. Ikkaku then comments on Iba's tone not sounding happy to which Iba retorts that happiness is the only thing a man feels when he is promoted so quickly. Ikkaku makes a point on Iba's work being all for his mother but Iba disagrees. Iba then points out that there was no more sake and they engage in a brief argument over Iba allegedly always drinking too much of Ikkaku's sake. The two have a few quick rounds of Jan-ken-pon (Rock-Paper-Scissors) and notice the Reiatsu coming from Sōkyoku Hill. Iba asks Ikkaku who is fighting Captain Kuchiki since he does not recognize Reiatsu. Ikkaku tells him that it is probably Ichigo with Iba then asking if he was a 11th Division member. Ikkaku answers back that he was a Ryoka, knowing due to fighting him before, commenting on the absurdity of an 11th Division member fighting Captain Kuchiki. Iba talks to himself a bit on how strong Ichigo is and on how nice it would be if he could fight him once (Ikkaku noting that deep down, Iba was still a member of the 11th Division). They then fight again (with the loser having to go acquire more sake)