Main Characters

Sumireko and Kaoruko Ichijou

Sumireko voiced by: Ami Koshimizu

Kaoruko voiced by: Yui Horie

Bettyand Veronica: Sumireko and Kaoruko share the Betty role to the Sakurazuki twins' Veronica.
Childhood Marriage Promise: Between them and Nozomu.
Identical Twin ID Tag: Sumireko wears her hair in a ponytail, Kaoruko has short hair.
Miko: Work at the Sourin Temple during the events of Futakoi Alternative

Yura and Kira Sakurazuki

Yura voiced by: Hiromi Tsunakake

Kira voiced by: Yui Itsuki

Bettyand Veronica: Yura and Kira share the Veronica role to the Ichijou twins' Betty.
Disappeared Dad: Their father travels most of the time, so they are raised by their butler.
Elegant Gothic Lolita: the Sakurazuki Twins' disguise as "Gothic Lolita Mask".
Girlish Pigtails:
I Just Want to Be Normal: They want to live among common people.
Identical Twin ID Tag: Kira wears red hair ribbons, Yura blue.
Mafia Princess: As granddaughters of a Yakuza boss, though they don't approve of their grandfather's legitimate business.
Ojou:
Twin Threesome Fantasy: Both are fine with sharing Nozomu.

Sara and Sojyu Shirogane

Sara voiced by: Kaori Mizuhashi

Sojyu voiced by: Mai Kadowaki

Childhood Marriage Promise: Between either Sojyu and Sara and their guardian, according to his father's will.
Feminine Women Can Cook: Soju
Hero of Another Story: The main twins in Futakoi Alternative.
Love Triangle: A mutually loving relationship with Rentarou.
Polar Opposite Twins: Sara is impulsive, assertive, and resolute. Sojyu is calm, submissive, and kind.
School Uniforms are the New Black: Sara and Sojyu are rarely shown wearing anything different besides what appear to be school uniforms.
Tsundere: Sara with Nozomu
Twin Threesome Fantasy: Sara and Sojyu would like nothing better, and Sara openly asks for it.

Lala and Lulu Hinagiku

Lala voiced by: Yurika Ochiai

Lulu voiced by: Shizuka Hasegawa

Hero of Another Story: In Futakoi Alternative, they are secretly fighting off a giant squid.

Ui and Koi Chigusa

Ui voiced by: Kozue Yoshizumi

Koi voiced by: Natsuko Kuwatani

Identical Twin ID Tag: Ui wears square-frame glasses and has a loose ponytail, Koi wears round frames and ties her hair in a braid.
Kindly Vet: Work at their father's vet clinic.
Megane: Both twins.

Ai and Mai Momoi

Ai voiced by: Chiaki Takahashi

Mai voiced by: Minako Sango

Two adult twin sisters who work at the same school most of the other twin sets attend, Ai being a teacher and Mai the school nurse.

Futakoi

Nozumu Futami

Voiced by: Motoki Takagi

Rentarou Futaba

Voiced by: Tomokazu Seki

Generation Xerox: A lot of people from town apparently thought that Rentarou would follow directly in his father's footsteps, and nick-named "Nidaime" (meaning "Second generation")
Love Triangle: Rentarou has a mutually loving relationship with Sara and Sojyu, but had a more traditional one with Ai and Mai.