/mono/ - Monoko/Monoe

I always imagined Monoe being the older sister of Madotsuki. I like to think that Madotsuki, Monoe, and Monoko played together as kids, but gradually Monoko and Monoe became closer, making Madotsuki the third wheel. Monoe became colder to Madotsuki, and pretty much ignored her in her teenage years. Sorta like Mitsuru and Makoto's relationship from Colorful. Like, she looked down on Madotsuki for being the "ugly duckling" of the family, but deep down loved her. Meanwhile, she favored Monoko, and often tried her best to lead Monoko to success. After the car accident, she was devastated, and decided to distract herself from the pain by dedicating herself wholeheartedly to her work. This lead her to become an extremely successful business who had high authority over everyone. But it also meant that all ties between Madotsuki and Monoe were lost, and Monoe viewed her as nothing more than a disappointment, a failure. Madotsuki wasn't even a sister to her anymore. This causes her to pop up in Madotsuki's dreams as her guilty conscience, as somebody who's "above" her. So she's an overbearing figure to Madotsuki.
I'm not really sure if this is a theory, though. Since it doesn't really have any evidence to back it up. It's only my opinion.
I apoligize for any mistakes in my writing, I didn't have a lot of time to write this.