Harumaki's unnamed Doctor is the physician placed in charge of the elderly Harumaki.
After being admitted to hospital, the Doctor stays at the sickly Harumaki's side along with Gyoko until Harumaki's grandson finds the person who Harumaki's been dreaming of. Once Harumaki's grandson locates Ranma and brings her to the hospital the Doctor explains that the next few days will be crucial to Harumaki's recovery. He then adds that Harumaki is currently "soul travelling" which allows his spirit to move about independent of the body.
When Ranma finally gives in and agrees to date Harumaki's spirit the Doctor stays with Gyoko to watch over his body to see what will happen. Once Harumaki stops soul travelling the Doctor tells the grieving Gyoko that making noise could be what stops her husband passing on. Desperate, Gyoko takes up the Doctor's advice and succeeds in waking up Harumaki.