Ikkaku Madarame was thrilled because he had learned that Ichigo Kurosaki had actually been trained by Yinsen. In Soul Society, Yinsen's most famous identity was not that of the former captain of the Tenth Division, but as the teacher of Byakuya Kuchiki, the current captain of the Sixth Division!
Byakuya Kuchiki was strong—many Shinigami knew that. As the renowned man who had trained Byakuya Kuchiki, Yinsen was still remembered by many even a hundred years later. Ikkaku Madarame, especially as the Third Seat of the Eleventh Division, had heard even more about Yinsen from his seniors in the division back then.
For example, when Yinsen had still been the lieutenant of the Fourth Division, he had beaten the Eleventh Division so badly that they no longer dared cause trouble in the Fourth Division. After Kenpachi Zaraki became captain of the Eleventh Division, he often scoured the Seireitei looking for people to fight, and frequently lamented that he had joined the Thirteen Court Guard Squads too late. Otherwise, he would definitely have sought that guy—Yinsen—for a proper fight.
With so many reasons, Ikkaku Madarame had also harbored the desire to challenge Yinsen.
It was not because he wanted to defeat Yinsen and uphold the Eleventh Division's reputation, nor because he wanted to make a name for himself. Ikkaku Madarame's thoughts were simple: he just wanted to fight a strong opponent once. That was all!
Unfortunately, Yinsen had been missing for over a hundred years. No one knew where he was now, or even whether he was alive. Though most people considered it unlikely that he was dead; Shinigami, especially powerful Shinigami, lived very long lives.
Who would have thought that among the Ryoka who had invaded the Seireitei, there would actually be that man's disciple?
To show his respect, Ikkaku Madarame