Kilmister (first name unknown) is a major character in On the Way to a Smile: Case of Shinra. A former Shinra scientist, Kilmister worked with Professor Hojo as an assistant when he was younger. An unspecified time later, after the Jenova Project, Kilmister left the company and opened a hospital in Kalm. He looks after Rufus's wounds while Rufus is captive in Mutten Kylegate's mansion.
When Kylegate is killed, Kilmister takes Rufus out of Kylegate's mansion to a cave, where he has quarantined people with Geostigma. Kilmister tells Rufus he has discovered a connection between Geostigma and Jenova, and is suppressing the pain of the disease using a diluted SOLDIER stimulant, but has had no success finding a cure. Rufus eventually sends Kilmister to meet with the Turks, and Kilmister recovers Hojo's research. With it, Kilmister discovers that the disease is more directly caused by Sephiroth, and tells Rufus the disease intensifies to fatal levels when the infected give up hope. The next day he is found dead, shot by a man named Judd who blamed Kilmister for his wife's death.
As an ominous aside, Kilmister tells Rufus he suggested a project to Hojo once that was rejected, but he still wishes to try. Though he does not elaborate, Kilmister tells Rufus he believes his project could create a being surpassing Sephiroth.