Hiromi Tsuru was found unresponsive in a car pulled over on the side of an expressway in Tokyo with its hazard lights on and was rushed to hospital but was pronounced Dead on Arrival. She is believed to have died from a heart attack. She was only 57.

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Link goes to a page on AnimeNewsNetwork.com

Anyway, although Madoka Ayukawa sang once or twice on the Kimagure Orange Road anime, her singing voice was provided by pop singer Yuiko Tsubokura. This one image song, so far as I can tell, is the only KOR song actually sung by seiyuu Hiromi Tsuru, Madoka's speaking voice.

Besides voicing Madoka and Bulma, Hiromi Tsuru was also the voice of Dokin-chan in Soreike! Anpanman, Ukyo Kuonji in Ranma ½, Sachiko Nishio in Touch, Asuna Kujo in Maison Ikkoku, Meryl Strife in Trigun, Mikami in Ghost Sweeper Mikami, and Kiddy Phenil in Silent Möbius, among many other roles.

Hiromi Tsuru hadn't been as active a voice actress over the past decade, but she had reprised her role as Bulma for Dragonball Super up until episode 96 (according to Twitter).

RIP