When we first meet Tohru of Miss Kobayashi’s Dragon Maid, she is unmistakably a dragon. With green scales, yellow eyes, and a body that doesn’t even fit within the series itself — only parts of her are shown until she raises her head above the forest and takes off in flight — Tohru is massive and clearly strong.
Yet, for most of the series, Tohru appears as the young woman above — a cute, busty cosplayer with seemingly limitless energy. She appears as what she believes will be the most desirable physical representation to her soon-to-be employer, Miss Kobayashi.
In their drunken first meeting, Miss Kobayashi not only invites Tohru to her home, but mentions that having a maid would be the best. We later learn that she had a very specific image of a victorian-style, traditional maid, of which Tohru knows nothing.
During her initial journey to Miss Kobayashi’s house, Tohru soars over a group of young women, dressed in costume, handing out flyers for a maid cafe. This is presumably her only experience with maids and she takes their appearance to heart, copying their outfit for her every day maid dress. When Miss Kobayashi asks Tohru to perform the duties of a maid, Tohru stands cutely in her living room with a sign, advertising “Maid Cafe Cozy” while handing out flyers.
Years ago in DokiDoki! Precure, an episode aired that showed the precures’ fairy partners transforming themselves into humans for a day. Their purpose was to aid their human counterparts in any way possible by becoming human. Furthermore, their varying physical appearances represented the different relationships that they had with their respective other halves.
For example, Davie — partner of Makoto Kenzaki (Cure Sword) — always appears as her manager. Makoto is currently undercover as an idol, and Davie not only provides her with moral support but also sees to it that Makoto’s work life runs smoothly. Sharuru, who wants to become a human exactly like her partner, Mana Aida (Cure Heart), looks like the spitting image of Mana when transformed, only younger, and so on.
Tohru’s transformation is similar. She becomes what she thinks Miss Kobayashi will want. Since her experience with maids is limited to what little she saw while flying, she quickly adopts this style of dress.
Even when Miss Kobayashi gives her every day clothes, Tohru still keeps her maid headpiece accessory when changed. She does remove this while sleeping; however, sleep is notably unusual for dragons. The fact that Tohru is sleeping at all also signifies her desire to grow closer to Miss Kobayashi.
Tohru’s horns, lizard-like eyes, and green tail remain as residual physical traits of a dragon. She is also visibly larger than Miss Kobayashi in every way. When they share a bed at night, Tohru’s giant tail peeks out from under the covers, curling on the floor. This is a nice testament to her strength and existence as a legendary beast, reminding us that when she was first introduced, she couldn’t even fit within the scope of the series’ camera.