Likes Older Women: Zig-Zagged in several different directions. On one hand, Makoto seems to be attracted to both girls his own age as well as Meme, who is 23 years his senior. On the other hand, he tends to ping-pong between attraction and repulsion towards Meme.
Nice Guy: For the most part. He has no hidden agendas while trying to help Erio open up despite what Yashiro may try to tell him.
Not so Above It All: In episode 3, after Meme leaves his room, the first thing he does is look outside the hallway to make sure no one's there. Then he jumps on his bed and sniffs his pillow where she was laying moments before. She then opens his door and tells him she probably doesn't have much of a scent because she wasn't wearing makeup.
Broken Bird: She claims to have lost half a year's worth of memory, broke her leg trying to fly while on a bike, talks about aliens and eventually earns a reputation to the point that she eventually becomes a recluse.
Does Not Like Shoes: She not only looks and behaves like she came from another world, she actually thinks she's an alien. Therefore, it's safe to assume that she doesn't will to try such an invention of the humanity as shoes, not even after some of the illusions of her being an alien were broken.
Hikikomori: As much as it's Played for Laughs, Erio is a textbook case, reacting to severe trauma by withdrawing from the world. The fact that Makoto looks confused and sasses her instead of pointedly ignoring her like everyone else in her life does — her mother included — is getting her to open up to him, slowly.
Magic Skirt: Considering how often the camera follows a low angle Male Gaze around her, Erio is lucky for this. There was a pretty unavoidable Panty Shot in the first episode, but it was censored with a flying saucer.
Multicolored Hair: Erio has very light blue hair but at times gains crystal-like glitter (that can flow off her without ending). Other characters notice this, mainly Makoto, but never mention it out loud.
Security Blanket: She finds it difficult to interact with people without having herself wrapped securely in a futon. Even after getting over the worst of this she finds it soothing.
Shrinking Violet: Social interaction-wise, after Makoto finally breaks her shell.
Theory Tunnel Vision: Erio was in a tragic accident wherein she went missing for three months and then turned up on a beach without any memory of the intervening time. Her reaction was so bad that she invented a story that she had been abducted by aliens and convinced herself that was the only explanation. After a few months, she tried to test her theory... only be injured again. But again, because she was far too fragile to face reality, she only drew even further into her fantasy world, to the point of becoming a Hikikomori. Later, her cousin forcibly proves to her that she isn't an alien, but after an initial highly negative reaction, she seems oddly okay and is even willing to regain society again.
Bumbling Mom: Meme does love her little girl, and the only time she's ever been shown to be serious was when she's thinking about her, but that doesn't stop her from showing she has absolutely no idea on how to be a parent.
Christmas Cake: Played with, already being a 39-year-old single mother who still hits on her nephew.
Makoto's highly energetic classmate and a member of their school's girls' basketball team.
Clingy Jealous Girl: Shows no reservations on expressing jealousy whenever Makoto hangs around with another girl in her presence. She will also invite Makoto to events, only to suddenly change plans whenever she sees or learns that Erio is tagging along.
Huge Schoolgirl/Statuesque Stunner: She tells Makoto that at 179.9cm, she is a magnet for school clubs, but due to her poor physical health (probably just being out of shape), they quickly lose interest in her.
She's Got Legs: Due to being so tall. Its most pronounced when she's wearing her various cosplay outfits.
The Tease: While not as much as Meme, she does occasionally invoke this trope, particularly when Ryuuko is around.
The old woman who owns the local sweet shop and employs Erio. A strong believer in aliens, who is convinced that she is being subjected to "cattle mutilation," causing her various illnesses. She is also Meme's grandmother.
Mysterious Waif: While Makoto treats her like a runaway brat, enough strange things occur when she's around to fit this trope, such as wearing a spacesuit in the middle of summer, along with some other strange coincidences.
Oracular Urchin: Argues for the existence of the supernatural long after Makoto punctures Erio's fantasies. At points, she almost comes just short of convincing Makoto himself that perhaps life isn't as ordinary as it appears.
Love Confession: Did one to Ryuuko before the start of the series, only to be turned down. This causes some awkward moments when she sees him playing on the town's baseball team, and he in turn shows up at her basketball game — even as he is already dating Hanazawa.
Determinator: While she was winning the preseason games between the city and shopping district baseball teams, she mentions to Makoto that they're constantly losing in the high school games. However, she mentions that she doesn't want to give up, unless their team just loses hope altogether and then possibly get disbanded due to lack of interest from students joining due to their poor track record.
Friendly Enemy: She is the ace pitcher of the opposing team to the Ragtag Bunch of Misfits that make up the shopping district team, yet is never portrayed as anything other than nice and polite to Makoto, Maekawa, or anyone else from the other team who interacts with her