Valencina & Lucio

In Yoshihide's absence, each of the five Nursefathers took in an apprentice and began teaching them for the purpose of one day using them to continue Yoshihide's training. The Thumb apprentice Lucio was trained by Valencina to be a "textbook" for Yoshihide to relearn her techniques, the Index Proxy Sora was trained by Rien, the apprentice Kira was trained by the Middle Nursefather Matthias, the apprentice Albina was trained by the Ring Nursefather, and the apprentice Ren was trained by Shiomi Yoru, becoming her mouthpiece as well.

After Operation Spider Pyre, the House of Spiders was destroyed, and all the Nursefathers and apprentices except for Kira were killed.

During her time in the House, Yoshihide was trained by the Thumb Nursefather Valencina in swordsmanship, specifically in the Palermitan Style. In the manner and culture of the Thumb, Valencina drilled in her training with physical abuse and emphasized the importance of manners; the Index Nursefather Rien demonstrated how to use various weapons, including a weapon known as "Zenon's Tortoise Spiral"; the Middle Nursefather Matthias was detached from parenting, and was instead eager to spend money on gifts for Yoshihide; the Ring Nursefather Callisto taught Yoshihide the principles of the art of the Ring, particularly the style known as Corporism; the Pinky Nursefather Shiomi Yoru trained Yoshihide in swordplay, teaching her all she knew. Several high ranking Finger members would also visit the house as temporary tutors, one of which was Lei Heng.

Once an adult, Yoshihide took a child, Araya, under her care. Having decided to sever herself and her family from the control of the House of Spiders, Yoshihide hid Araya away in a safe she'd hidden in the House, which used T Corp. technology to alter the passage of time, and she cut her way through the Nursefathers, severing Shiomi Yoru's tongue, Valencina's eye, Matthias's right arm, Callisto's artwork and burning half of Rien's face, before making her escape. It was revealed that Shiomi Yoru was also stabbed in the heart by Yoshihide, resulting in her death. The Pinky Nursefather was later replaced by Araya, after leaving the safe prematurely and being confronted by Rien.

The House of Spiders is an organization whose objective is to raise an individual through the culture and fighting techniques of the Finger syndicates, in order "to forge a blade that cuts through all." The true purpose of the group was to create a wielder of the Relic Arayashiki that could permanently erase anything that it cut down, creating a being akin to a living Concept Incinerator through the use of transforming Ryōshū into the Muga, causing the wielder to be elevated into emptiness and nihility, as the price for using the sword was the loss of one's memory. Though the Muga and a Concept Incinerator are similar, they are differentiated as the Concept Incinerator "deletes" an object or concept, while Muga isolates and untethers whatever is brought into its path. A Muga-destroyed concept still exists, though is inaccessible and assumed to not exist by any external sources of interaction. The organization has been operational since around the year 957, nearly three decades before the beginning of the main story, coinciding with the birth of Ryōshū, then known as Yoshihide, and has remained active since.

The members of the House were five high-ranking, yet largely disgraced members of the Five Fingers: a Sottocapo of the Thumb, an Oracle's Proxy of the Index, a Great Brother of the Middle, a Maestro of the Ring, and a Star of the Pinky. These five were the House's Nursefathers, and they were responsible for Yoshihide's upbringing and training, which took place in a massive building in a secluded location, connected using the Ring's Corridor technology. While a number of other members of the Fingers were aware of the location of the House and could visit it, the Pinky Nursefather, Shiomi Yoru, was tasked with looking after Yoshihide and therefore forbidden from leaving its premises.

You can be whatever you want to be here, just... try not to cross the line.

The Thumb's hierarchy system features four major ranks, which are then divided into multiple sub-ranks. The ranks are as follows:

Soldato (Soldier): The common foot soldier of the Thumb, and the lowest rank possible. "Common Fixers" are equivalent in rank to them. The Soldato rank is divided into four sub-ranks: Primo, Secondo, Terzo, and Quarto.

Capo (Captain): Those who command groups of Soldatos, relaying orders from their higher-ups. They are able to act with more liberties. A Grade 1 Fixer is considered equivalent in rank to a Capo. The Capo rank is divided into four sub-ranks, likely the same sub-ranks as Soldatos.

Consigliere (Advisor): A member or members with sway over the decisions of the Capo dei capi and advising them. They appear to handle the instatement of particular members of the organization, with at least a "central" Consigliere directly answering to the Capo dei capi for these matters. It is unclear whether the rank belongs to more than one individual at a time.

Sottocapo (Underboss): The direct underlings of the Capo dei capi, who have permission to manage entire operations of the Syndicate within designated areas. They also manage the Thumb's 'families' of subsidiary Syndicates, each Sottocapo being assigned a different one. Top-ranking members of a Wing are of equivalent rank to a Sottocapo.

Capo dei capi (Godfather, Padrino): The highest echelon. It is unclear whether the rank belongs to more than one individual at a time.

Overview: Like the other four Fingers, the Thumb is a large Syndicate with a unique culture and creed that all members follow fervently. In particular, members of the Thumb value politeness and respect to one's superiors above all else. In practice, this means that the Syndicate demands absolute compliance to hierarchy, as when dealing with the Thumb, any action that demonstrates a lack of respect for higher authority will be met with immediate punishment. Depending on the mistake, the consequence may extend past the rule breaker, to even their blameless comrades.[6] Ultimately, the Thumb will punish anyone it deems an offender, regardless of how innocent the mistake or clueless the individual is. Members of the Thumb also understand their own need to respect outsiders, and may spend time studying the hierarchy of other City factions in order to ensure they never disrespect someone of a higher rank. Thumb punishments tend to revolve around the removal of body parts, such as body dismemberment or the forceful removal of one's tongue.

While the shape of the Syndicate differs slightly depending on the quadrant of the City, members tend to dress in black, red, and gold attire. Each member's status can be gleamed from their uniform, as the Thumb signifies its ranks by the number of arrows on its badges, and sub-rank by the number of pins on its collars. The Thumb's weapons of choice are guns, which they make varied use of—such as through fighting with the bayonet or buttstock—in order to cut down on bullet costs.

Appearance: Lucio is a tall man, with violet eyes and light gray hair split neatly to reveal his face, tied into a long ponytail that reaches his waist. He wears a Thumb uniform consisting of a rose-red vest, trousers, and a neatly buttoned ivory shirt fastened with a dark red tie, with his sleeves rolled up past his forearms. His hands are covered by rose-red gloves of the same color as his vest and trousers. His vest is fastened by two suspenders which connect to a belt, with a golden pin with one arrow pointing rightwards on his left breast. He carries two golden swords contained in wine-red scabbards, with gilded hilts and tips on the scabbards - one longsword with a striped pattern on his back, the other smaller with a spiral pattern at his left hip.

Personality: Quiet and steadfast, Lucio carries an air of professionalism unlike his mentor. Even in the face of immense adversity and scolding, he remains calm and collected, ready to continue his efforts even while confronted by the possibility of loss. Given his role as a possible tutor, he is expected to be prim, proper, and dutiful. Though he frequently criticizes his opponents' forms in combat, his words are not as harsh as his master's, as he attempts to use them as a point of growth rather than disappointment.

Despite Valencina's abuse of Lucio, he feels permanently indebted to her for feeding and sheltering him, and is not willing to admit to her cruelness when asked. However, his combat passives demonstrate that he actually burns with resentment towards her, and has long been aware of her depravity, considering it his responsibility to eventually take her life.

Appearance: Valencina is a tall, older woman with sea green eyes and long, dirty blonde hair that covers her right eye. She wears a Thumb uniform consisting of a rose-red jacket, trousers, wide brimmed hat and untied ribbon over an ivory shirt with the top buttons undone. The right lapel of her jacket has a golden pin with one arrow pointing rightwards. She is seen smoking a cigar, and has black gloves with light palms. She is said to have the Relic "the Eye of Odin" in place of her right eye. As Ryōshū damaged the Relic using Arayashiki, the wound reopens when Valencina is in its presence, at one point causing a cascade of blood to cover her face.

She carries two swords, one being a straight sword with a revolver barrel at its guard kept in a red sheath, and the other, a curved sword with yellow ribbons on its grip kept in an orange sheath. Both have golden, ribbed blades.

Personality: Valencina is an arrogant, booze-loving woman with a violent, foul-mouthed personality. She has a short temper, immediately taking towards physically attacking Lucio following a perceived failure on his part, as well as frequently harming the young Yoshihide during their training sessions. While she aims to benefit greatly off the cultivation of Ryōshū's abilities, she generally regards the woman in contempt, even while she was still under the care of the House of Spiders. She remains extremely bitter about her expulsion from the Thumb and fall from grace, and is obsessed with making others give her the respect she's owed (Still, she is not a bad woman, i mean, she kinda appreciates Lucio)