She has 2 different appearances, Normal (Real World) and Honmaru appearances.
Her birthday is on 28th February
Registered as a Saniwa when she was 17 years old
"Protector" - ISFJ
Height 158cm
Blood Type : O
Zodiac : Pisces
Chinese Zodiac : Pig
Birth flower : Greater Periwinkle (蔓日日草の丸)
Birth Stone : Amethyst
Traits : Reckless, Straight-forward, Earnest
Her hair is styled by Hachisuka Kotetsu
Her honmaru attire is designed by Kasen Kanesada
She can go to the battlefield, but will trigger Kebiishi everytime she went
Currently don't have romantic relationship with any canon character, but Kikkou has romantic feelings towards Shiromi.
2flheimr can't be said as a black honmaru, but also not a white one. Everyone is working hard, but also has enough rest. Currently 2flheimr is quite abundant financially. Everyone is living comfortably with the current financial state.
Shiromi tried to treat all 100+ touken danshis equally. She saw them as her possession, and treated them as fellow humans most of the time, but sometimes will use them as a tool depending on the situation.
Deep down, Shiromi knows that she won’t be able to oversee her honmaru forever. So she has been preparing the Honmaru so they can operate as usual even if Shiromi is not there anymore.
Elivagar
Shiromi Matou's first Honmaru, currently inactive/dormant. Linked to 2flheimr and able to access 2flheimr's facilities.
2flheimr
Shiromi Matou's second Honmaru, currently active.
Illustration by Airy Aracia
Previously, from The Second Honmaru, it has been told that 2flheimr is Shiromi Matou's second Honmaru. In this universe, one person can't have multiple Honmaru, but Shiromi Matou ended up in 2flheimr because she experienced a malfunction in her first Honmaru.
Shiromi Matou went through the passage of time to return to her own timeline, and registered for the second time as a Saniwa. That's why Shiromi Matou went through Saniwa's Inauguration twice. This made some difference between Shiromi Matou and other Saniwas.
Because she went through the passage of time, she messed up the timeline and erasing another [potential] timeline completely, it made another version of her, whose now known as Fuyu no Tsurugi got transported to Shiromi's first Honmaru. The Government of the Time is tempering with every Saniwa's timeline. That's why, once a person become a Saniwa, they don't have the choice to split the timeline anymore and stuck to one timeline.
If the [Fuyu no Tsurugi's Timeline] exist, the secondary timeline will be able to branch just like any ordinary human. But, because of [Fuyu no Tsurugi's Timeline] disappearance, Shiromi's timeline got concentrated only in one timeline instead. This made Shiromi Matou became one anomaly just like Fuyu no Tsurugi. Thankfully, the Government of the Time haven't detected Shiromi Matou's anomaly yet.
These are some abilities Shiromi gained because of those events.
Passage of time exist for Touken Danshi to be able to travel through time to protect the history. Saniwas shouldn't be able to travel through time using this passage. But Shiromi used it once when her first Honmaru is malfunctioned. This made Shiromi able to use the Passage of Time, but if she did that and went to a battle field, she will trigger Kebiishi/Justicar.
Except for the first time, Shiromi never intentionally travelled through the Passage of Time. Not all Touken Danshi knows about this ability of their Saniwa.
Being awakened as a Saniwa twice made Shiromi able to inherit the previous Sword's memories to the sword duplicates. But memory inheritance is different with sharing the same experience. The way a duplicate inherit the memory from their previous counterpart is like watching a first-person's POV movie.
Memory Inheritance only happen on the first summoning, and the individual Touken Danshi will still be a different individuals with their duplicate(s). After summoned for the first time, a Touken Danshi won't be able to read the memories of their duplicates.