Karen and the eleven other sisters are is excited to meet their beloved big brother again! They bustle about town to get ready for his arrival, and mishaps befall them as they do, but Big Brother's understanding knows no bounds.

Kaho prepares a special gift for Big Brother, but it goes missing! Luckily her sister, girl detective Yotsuba, is determined to solve the case. Afterwards, Mamoru remembers how she struggled with her tomboyish nature until Big Brother helped.

Kaho weighs herself, and the results are devastating! She goes on a diet, but it's hard for her as Big Bro and her sisters enjoy sweets together. Afterwards, Aria finds herself in a mysterious, magical mansion...

Kaho's staying over at Big Brother's place, and she buys cute new pajamas with her sisters' help. They have a fun-filled evening together. Afterwards, Hinako goes out in the rain and faces her fiercest enemy yet: a frog!

A strange girl who looks like Chikage gives Big Brother a ticket to the planetarium... then, later, demands it back! It's not easy, but Big Brother solves the mystery. Afterwards, Kaho remembers the pretty red shoes she got long ago.

Big Brother and the sisters go on a camping trip. Mamoru had a gift for Big Brother, but will she get the chance to give it to him? Afterwards, Rin Rin remembers how her grandpa taught her to love inventing things.

Aria spends a day with Big Brother, but she's sad when it ends... so she hatches a plan to make him come back! Afterwards, Chikage prepares a sinister ritual to win Big Brother's love for herself alone.

Rinrin and Yotsuba get curious about what Big Brother does when he's out alone, and decide to follow him secretly around town. Afterwards, Haruka thinks about her first Tanabata festival together with Big Brother.

Big Brother gets a love letter! Sakuya decides to stick close and protect him from his other admirers, but can she confess her own feelings? Afterwards, Marie has a sweet dream of her brother.

Sakuya is heartbroken when Big Brother doesn't recognize the gift he once gave her. She runs away and wanders the town, awakening her own memories of her time with Big Brother. Afterwards, Shirayuki reminisces about how she learned to bake and make sweets.

Thanks to Sakuya's hard work, the sisters go to a fancy restaurant with Big Brother and have a lovely evening. Afterwards, Sakuya dreams of being Big Brother's bride and getting married in a church.

Big Brother and the sisters get ready for a special Christmas together, but none of them can decide on which present to get for their brother until they have a brilliant idea. Then Big Brother works hard to make sure the Christmas tree is perfect!