Doc

An elderly doctor who manages a private clinic with a nurse.

Plot
He appears to know Ryo and Kaori well. Glass Heart was put in his care after passing out and later under further medical observation. He has most of her medical records. He appears quite often in the anime.

Kaori Makimura
Kaori has worked at his clinic when she was younger then as a nursing student. He has some personal medical knowledge and information about her.

Ryo Saeba
He first met Ryo when Kaori brought him to his clinic after suffering a gunshot wound. Seeing his participation along with Ryo in the 'Kabuki Street Barricade' incident with the Green Dragon Division, their acquaintance is likely close friends that has mellowed over time.

Xiang Ying
Since brought to his clinic, they have gotten better acquainted from there forth. She has become his patient and he now holds most of her medical records.