Bubuki Buranki: Rivals

Close-up of Asuma Kazuki and Kaoruko angrily butting their heads together

Buranki are giant, sentient, robotic beings, and both Azuma Kazuki and his younger twin sister, Kaoruko, have the power to awaken and use the one known as Oubo, though they disagree over who has the right to possess its control-unit “heart.”
From the anime series Bubuki Buranki

Gakusen Toshi Asterisk: Students of the Yellow Dragon

Shenhua Li and Shenyun Li wearing pink fighting clothing

Shenyun Li and his younger twin sister, Shenhua, are both arrogant and ruthless but highly skilled fighters who enjoy making their opponents suffer in the arena.
From the anime series Gakusen Toshi Asterisk (The Asterisk War: The Academy City on the Water)

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!

Selector Infected WIXOSS: So Close Yet So Far

Kazuki Kurebayashi and Yuzuki Kurebayashi standing back-to-back against a pillar of pink light

Yuzuki Kurebayashi fights as a Selector in order to make her wish come true. Her younger twin brother, Kazuki, helps her whenever possible, even though he doesn’t know her true desires.
From the anime series Selector Infected WIXOSS

Joukamachi no Dandelion: The Royal Bunch – Part IV

Misaki and Haruka Sakurada in school uniforms

Fourth princess Misaki Sakurada enjoys being with her younger twin brother, the reliable second prince, Haruka, and he is happy to support her in whichever ways he can.

From the anime series Joukamachi no Dandelion (Castle Town Dandelion)

Joukamachi no Dandelion: The Royal Bunch – Part III

Aoi, Shu, Kanade, and Akane Sakurada in a neighborhood

Aoi Sakurada, the blue-haired first princess, is the most favored to win the election to succeed the king. Her younger siblings, Shu the first prince and Kanade the second princess, are twins who are diametrically opposed when it comes to their interest in winning. (She cares; he doesn’t.) Meanwhile, Akane, the shy third princess who often hides behind her older siblings in public, prefers to live life out of the spotlight.

From the anime series Joukamachi no Dandelion (Castle Town Dandelion)

Joukamachi no Dandelion: The Royal Bunch – Part II

Campaign posters for the nine Sakurada siblings

Vote for Sakurada! Aoi, Shu, Kanade, Akane, Misaki, Haruka, Hikari, Teru, and Shiori are all good candidates.

From the anime series Joukamachi no Dandelion (Castle Town Dandelion)