Takashi had his left arm under Koharu's legs, to help keep her balanced on his back. Takashi had told both the girls that the zombies are attracted to sound so they had to keep quite for Takashi to slip past them without any trouble.

Koharu kept her mouth shut as she looks in the horde of zombies in the streets, she can see about a dozen other zombies in different school uniforms in the horde. But she was snapped out of it when she heard something that made her freeze as well as Takashi, when they were halfway past the horde.
"Um excuse me? What did you say?" Whisper's Takashi, with a heavy blush on her face, Arisu repeated what she said; "I gotta pee." She whisper's again and Koharu whispered to her little sister to think about something else but when Arisu said that could not hold it anymore.

To suck up his male pride, Takashi tells the 7 year old that she can pee where she is. Once Arisu is done, Takashi was about to keep going when the hand of a zombie housewife grab his shoe lance and almost pulled the survivors off the fence. If Takashi didn't act fast and balanced them on the fence again, they would of been zombie food.

But then a loud engine reached the survivors ears, and when they looked up the road they saw Saeko Busujima standing on top of a humvee in the frilly white apron and her black thong and wooden sword, in hand.

Kohta Hirano has a shot gun, and is in the hatch between her legs as the humvee full of the supplies and friends come charging at the zombie horde.

Inside the humvee, the group sees the horde: "Ah there is so many!" Gasped Shizuka in the drivers seat, Aoi was is the passager's seat next to the school nurse, "Doesn't matter, we can't just abandoned Takashi and those girls!" Aoi said, and Saya who was sitting between the girls shouted, "RUN THEM DOWN!!"

And that is what Shizuka did as she ran over the zombies in her way until she got to a cross section of the two blocks. It was closer to Takashi and the girls as they were still making their way to the humvee. Kohta and Saeko took it as their jobs to clear the zombies away from the humvee and to clear out another path for the humvee to past through.
And Saeko is a badass to calmly walk away from a group of zombies after she killed two dozen of them on a street that the humvee will go next.

With the encouragement from Takashi's friends from Fujimi he made a big jump from the end of a fence to the humvee. And once he was safely on the top of the humvee with Saeko, Shizuka drives off the down the street with Takashi landing face first into Saeko's breasts and Kohta to fall inside the humvee with Koharu landing on his stomach and Arisu with her puppy falling on Kohta's lower reagen causing the boy to pass out while the girls apologized.
As the large group of students from different schools drove off away from the bridge and going down the river until they get to shallow waters.

Now once they cross the river, they just need to find their families in the residential area. And where the schools on that side of the river are being used as evacuation shelters.