Medaka Box: Class 13 Perverts

Myouri Unzen looks at Myouga Unzen who holds two giant iron balls

Myouga Unzen and her younger brother, Myouri, both possess unique abilities, an affinity for spherical objects, and dirty minds.
From the anime series Medaka Box

The Family Fang: Filming

Baxter Fang holds a camera while he and Annie Fang observe

As adults, Annie Fang and her younger brother, Baxter, are both still trying to come to terms with the fact that their conceptual performance artist parents used them in their controversial, avant-guard work.
From the movie The Family Fang

The 5th Wave: Who’s That?

Cassie Sullivan and Sam Sullivan standing in front of greenery and looking at something

Will Cassie Sullivan and her little brother, Sam, survive the next phase of the alien invasion?
From the movie The 5th Wave

Fullmetal Alchemist: Brotherhood: Bring It On

Alex Armstrong and Olivier Armstrong staring angrily while covered in blood

Don’t mess with Major General Olivier Armstrong or her younger brother Major Alex Armstrong.
From the anime series Fullmetal Alchemist: Brotherhood

Eve no Jikan: Memory

The Sakisaka family, as viewed by their new house android, Sammy

In a time when androids are used as everything from construction workers to housekeepers, Naoko Sakisaka sees them as mere things, while her younger brother Rikuo’s views change over time.
From the anime series Eve no Jikan (Time of Eve)

Amanchu!: Merriment

Makoto Ninomiya and Ai Ninomiya wearing wetsuits in front of a polka dot background

When Ai Ninomiya is not busy kicking her younger twin brother, Makoto, for fun, the two enjoy going scuba diving.
From the anime series Amanchu!

HaruChika: Haruta & Chika: Over There

Minami Kamijou and Haruta Kamijou looking to the left while standing in front of a building

Minami Kamijou is oldest sibling in her family and works as an architect, while her brother, Haruta, is the youngest, the only male, and still a student in high school. They have two middle sisters, Tsumugi and Fuyuna, (never shown in the anime) who annoy Haruta to the point that he moves out of the house.
From the anime series HaruChika: Haruta & Chika