Keiko Arima is Miyako Arima's mother. She and her husband, Fumio Arima, took care of Shiki Tohno during his time away from the Tohno family.
 

Shiki Tohno sustained a life threatening injury as a child, and due to that incident he was sent away from the Tohno household and was given to a relative to be raised. Years later, when Shiki is in high school, the head of the Tohno household&mdash;his father&mdash;dies, and he is ordered to move back in by his sister Akiha, who is the new head of the household. However, Shiki holds a huge secret. Ever since that injury, he has been seeing lines on objects, and only with a special pair of glasses is he able to stop seeing them. Also he is unable to remember anything well from the time before his accident. The day he moves back to the Tohno household is the day he stumbles upon a woman named Arcueid Brunstud and decapitates her with one stab of his knife in a temporary fit of insanity. When she suddenly showed up beside him later alive and well, and ask him to be her bodyguard, Shiki's journey to unravel the mysteries of his past begins.
 
(Source: Anime News Network)

Shiki Tohno sustained a life threatening injury as a child, and due to that incident he was sent away from the Tohno household and was given to a relative to be raised. Years later, when Shiki is in high school, the head of the Tohno household--his father--dies, and he is ordered to move back in by his sister Akiha, who is the new head of the household. However, Shiki holds a huge secret. Ever since that injury, he has been seeing lines on objects, and only with a special pair of glasses is he able to stop seeing them. Also he is unable to remember anything well from the time before his accident. The day he moves back to the Tohno household is the day he stumbles upon a woman named Arcueid Brunstud and decapitates her with one stab of his knife in a temporary fit of insanity. When she suddenly showed up beside him later alive and well, and ask him to be her bodyguard, Shiki's journey to unravel the mysteries of his past begins. 
(Source: Anime News Network)

Based on the Doujin Fighting game, 'Melty Blood', made by the Doujin group, Watanabe Seisakujyo now known as French Bread. The story is one of two side-story sequels that occurs approximately a year after the good ending story of Arcueid's from the original Type-Moon game, Tsukihime. 

One year has passed since the "Serial Vampire Homicide case", that occurred in Tsukihime, was solved. But now the rumors of the serial murder are happening again and so once more Shiki Tohno patrols the city to find this phantom killer. While patrolling he meets and fights a mysterious woman by the name of Sion Eltnam Atlasia, member of the church group 'Alchemist of Atlas', who is in search of curing vampirism. But to do so she needs data from Arcueid, the last True Ancestor, to help her in her research. But this wont be easy as Ciel is also patrolling the city looking for the rumored killer, while Akiha has been acting strangely the past few days and also Arcueid hasn't been seen for awhile, could she be the killer...?

The curtain rises on Shiki's feverish Melty Blood battle!
 
Tohno Shiki and Arima Miyako challenge 'Melty Blood: Type Lumina', the fighting game based on 'Tsukihime -A piece of blue glass moon-'! In addition, Arcueid, Ciel and other characters also get involved... This is an introductory manga to help you enjoy playing 'Melty Blood: Type Lumina'!