In the Light Novel Ema is much more independent and head strong, although she still has scatterbrained meants, such as when Fuuto asked her not to call him by name at an entertainment store but she did anyway. Unlike in the Anime, Ema is much better at pulling away from the brothers when they flirt with her.
There is a sub-plot in the Light Novel where Ema deals with hidden emotional trauma from her childhood, such as breaking down into tears when Masaomi told her he became like a father to Wataru because their father died shortly after he was born.
Ema first met Masaomi when she first arrived at Sunrise Residence where Wataru almost hit her with his bike, Masaomi quickly apologized for his little brother and went to find Wataru. Ema did not know they were her new brothers.
Ema first met Subaru when his was introduced along with Iori and Yusuke on her first day in the house, however he did not greet her properly. The next morning Ema finds Subaru and Kaname resting on the living room couch after their morning walk, Subaru is again quiet and still will not greet her properly, causing Ema to wonder if she did something to anger him.
5:00am, on June 22, exactly one month after Ema moved in with the brothers, Ema takes a bath and ignoring Juli's warning she walks down to the kitchen in only a towel. There she runs into Subaru, who is only wearing underwear after morning training (he forgot that Ema was now living at the house). Subaru turns deep red and stares at Ema in shock until Juli begins to rage from the living room and Ema flees the kitchen and takes Juli with her. At breakfast things are awkward between Ema and Subaru, so he quickly eats his meal and leaves the room.
In July everyone goes to Miwa's private island for Summer vacation. Ema wears a bikini to the beach, which causes Subaru to become shocked and surprised at the same time. He gives her his parker and tells her to wear it. Later that day, after a down poor, Ema pulls on Subaru's wet clothes saying that she will wash them as a sign of gratitude for the parker, which causing him to become shocked and surprised again.
Learning that Ema caught a cold, Subaru left some ion drinks on her door handle.