Urahara knows when to appear.
Rangiku is trying to push off some paperwork to Isshin but finds that Isshin left a note saying that he has gone to the human world.
In the human world, Masaki returns home and is confronted by Ryuu's mom about helping a shinigami. Ryuu sees this and confronts the maid Katagiri about telling what happened to his mother, and Katagiri explains that she didn't keep the secret because Masaki was injured and the Quincy bloodline depends on her and Ryuu. Ryuu goes back to take responsibility for Masaki's actions for suddenly Masaki faints and falls to the ground and a hollow hole begins to appears at the base of her neck. Ryuu carries Masaki and runs out of the mansion. Ryuu's mom yells for Ryuu to come back, but for some reason she is unable to leave the house.
Outside, Ryuu is targeted by a hollow but Isshin kills the hollow before it can hit Ryuu and Masaki. Seeing Isshin, Ryuu starts blaming Isshin for what's happening to Masaki, and suddenly Urahara appears and offers his help in saving Masaki.
The whole flashback is playing out quite nicely. We know Kubo sometimes like to pull out random crap, but this story about why Ichigo is so special seems to be well developed. Aizen's hollow was designed to attack and hollowfy a shinigami, but that apparently works on Quincies as well. Masaki is infected and starts to hollowfy, and this is where Urahara come in and come up with the solution. Masaki getting hollowfied certainly explains how Ichigo had the characteristics of the special hollow (and had a Fullbring). We still have to see how this leads to Isshin staying in the human world and marrying Masaki.