Niki Oogura is an alias she has sometimes used.
She has dark purple neck length hair and like Sekai, she has idiot curls, only twice as much as Sekai.
She is briefly mentioned by Sekai.
During the event of Shiny Days, Niki and Hanon attempts to gather a group of girls that want to engage in compesate dating along with them. The two pass by Setsuna at Haramihama Station but didn't speak with her as Niki isn't sure that it is her or not. Later, Nki runs into Inori while she (Inori) is looking for Sekai's apartment and is later reunited with her. Sekai and Setsuna were childhood friends with her until middle school, and Sekai chose not to associate with her because Niki's always looking for trouble. It is made apparent when she tries to set up Inori to sell her provocative pictures online and she is susprised at Inori's calibracy. Niki laters inform of Hanon (who is having sex with her customer in a hotel) about Inori's refusal while proclaimed to herself(which implied that she is not a virgin).