Lala Hinagiku

Futakoi:
The youngest twins in the series who live with Nozomu, their mother Miyabi, and pet goat Billy. They are affectionate towards Nozomu and claim him as their future husband which makes Billy jealous. [Wikipedia]

Futakoi Alternative:
Lala Hinagiku is the twin sister of Lulu Hinagiku.

(Source: Wikipedia)