Pretending to be dating the school Prince has its benefits, like when Sata comes with an umbrella to take Erika home in front of a jealous Marin and Aki. But its immense costs of the lie are starting to mount, and I’m not just talking about her self-esteem: half of the school is in love with the Prince, and all agreed to a “look but don’t touch” policy to keep the peace.
Between the resulting abuse from that at the continued humiliations she has to suffer when no one’s looking, from holding his umbrella for him to serving as a shield for car mud, to having to actually fetch a stick, one would imagine Erika is getting tired of this charade, which would mean Sata is winning. Her real friend Sanda tells her to just give it up and find a real boyfriend, or at least look for viable alternatives to the Black Prince, or otherwise quit griping.
Erika for her part is aware of the shabby treatment she’s enduring, but part of her sees it as a battle of wills: she knows Sata is going the extra mile to torture her, and she’s not going to surrender so easily. Sanda perhaps rightfully sees it as simple masochism on Erika’s part, but she doesn’t actually enjoy being treated like this. She’d like a little romance, like the kind she still sees in Marin and Aki’s relationships. (For all we know, they’re both lying too!)
She finally experiences some, or at least a very realistic simulation of it, in her interactions with Kimura, after surveying the field of guys and finding them lacking (an amusing mini-montage). Because Erika hasn’t so much as fallen for a guy before, she’s particularly vulnerable to deception, and Kimura fools her hook line and sinker, along with us, right up until she admits to him she’s not really Sata’s girlfriend.
Since the whole point of Kimura being nice to her was to steal her from Sata for revenge, he drops the act like the flipping of a switch, even rubbing it in what a cheap moron she is for falling for his ploy. That’s when Sata reveals he’s been stalking them the whole time (!) and despite saying he hates violence, clocks Kimura. While he’d never admit it, Kimura did succeed in making Sata jealous.
This is where the show makes the argument that despite the fact both guys objectify and use Erika by exploiting the weaknesses in her personality, Sata is the lesser of two evils…and in this, it mostly succeeds. Sata, after all, doesn’t seem to be maintaining the boyfriend fiction for any ulterior motive I’m aware of; his behavior towards Erika is a lot more sincere, even if he does code it with unfortunate pet dog references.
There’s also the notion floating around that while Kimura hurts Erika for no real reason other than spiting Sata, Sata’s dog-and-master act seems to come from a buried desire to reform Erika. He’s not saying it, but his actions scream “Things don’t have to be this ridiculous. If you don’t like the way things are between us, you have the power to change it. His latest heroics have her heart starting to skip for him; will she garner the will to abandon her lies and games?
It still seems there’s a legitimate risk in doing that, as Marin and Aki would surely not take kindly to learning she lied (again, even if they’re lying too) and she’d still have the scorn of every girl who likes Sata. And even after all that, Sata might reject her, like he rejects all girls. The risk is acceptable, and preferable to continuing to maintain falsehoods that open her up to intentionally shabby, degrading treatment. But that doesn’t make Erika’s choice any easier.