"Another building destroyed... I wish Miss Reimu would prevent property damage..."
Toshiri is a Termite Youkai who lives right on the boundary between Gensokyo and the Underworld. She has the ability to control the strengh of things, able to make them stronger or weaker. She uses this ability in her construction work to ensure her buildings are strong and resistant to damage, or make buildings weaker when they need to be demolished. Despite this, she is often busy due to frequent incidents causing damage. Outside of her work, she has an interest in rocks and ore, having a small collection in her home.
She is fairly introverted, and is very blunt and monotone in speech and expression. She speaks less than she listens, and doesn't tend to consider manners too deeply when she does speak, leading to some considering her impolite. She does emote occasionally, though they are small, such as small smiles and frowns or a light blush. She is written to be autistic, based on my own experiences as an autistic person.
Due to being a termite, Toshiri eats wood, including wooden items she percieves as discarded. This has gotten her into trouble in the past, such as when she ate one of Ichigo Seikaryu's wooden baskets.
Toshiri's name is a combination of toshi (利) meaning benefit or advantage, and -ri (里) meaning village. Her surname, Isoptera, is the infraorder which includes termites. Her title and associated tumblr tag, "termite builder of hell and earth," relates to her working in both gensokyo, the underworld and Old Hell.
Appearance wise, the two long sections of her hair are intended to resemble mandibles, which paired with her antennae emphasises the insect themeing. Similarly, the colours in her hair are intended to reference the colours present on the bodies of various species of termies. In terms of her specific species, she is an Eastern Subterranean Termite, but she does lack any features that specifically define her as this species. Her skirt has a woodgrain pattern, and her tights have holes torn in them, intended to reference the fact that termites eat wood. She near constantly wears her gloves and toolbelt, wears a hard-hat with a light when underground, and wears a coat over her shoulders in cold weather.
The shape of her hair, as well as her hard hat, are rounded to reference the round heads of termites.
Relationship with Kurodani Yamame
Toshiri and Yamame are in a romantic relationship, being girlfriends and unofficial business partners as Yamame occasionally helps Toshiri with parts of her work. Despite their differences in personality and expression, with Yamame being significantly friendlier and more open, the two get along incredibly well and have a healthy relationship. Toshiri values Yamame's kindness towards her and admires her bright personality, and is drawn to her strengh and aid in construction.
Though Toshiri isn't particularly fond of PDA, she often spends her spare time making or finding gifts for Yamame. Before the two got together, Toshiri was very nervous about this, and sought assistance from Ichigo and Kamine* to ensure she could make Yamame happy and comfortable. She isn't one to initiate much physical affection, but she will start the odd hand-hold or intentionally brush hands, and enjoys Yamame's acts of physical affection as well. Toshiri finds Yamame to be very beautiful, though she struggles to figure out how to express this. She also admires Yamame's danmaku, views her webs as art, and is impressed by her ability to manipulate disease. Toshiri enjoys taking Yamame on walks in the forest, or visiting Mystia's Izakaya together when it's quiet, but she is willing to go almost anywhere alongside Yamame, and is willing to brave places she finds overstimulating for small periods of time if it will make Yamame happy. Yamame is understanding of Toshiri's sensory issues, and while she appreciates her willingness to stray outside her comfort zone for her, she would never force Toshiri to push herself to extreme overstimulation or a meltdown for her.
*Both Ichigo and Kamine belong to Aesop