Think I remember hearing that the original idols had names that had something to do with ships or naval history. I dunno about that, but I've seen more than a few trains or train stations bearing the same names as some of the idols.
So meh. Instead of breaking down the names (which only have meaning if the writers feel like it), I'll just go over things that bear the same names as the idols, right down to the kanji unless I say otherwise. Happy coincidence time, go.
The Azusa (and the Super Azusa) is a train line that runs from Shinjuku to Matsumoto.
The Miura Peninsula just south of Tokyo is the location of the National Defense Academy of Japan. It also houses naval bases for the Japanese Marine Self Defense Force, and for the American Seventh Fleet (in Yokosuka, Kanagawa Prefecture). Commodore Perry also landed here (in Uraga, Kanagawa Prefecture) with his gunboats to try to get Japan to modernize.
Takatsuki Station is a stop in Takatsuki, Osaka Prefecture. It sits between Kyoto and Osaka on the JR Osaka Line.
Amami... pronounced another way is Tenkai, a Buddhist monk who advised the Tokugawa shogunate (also known as Nankoubou Tenkai). Video game fiction writers have a heyday painting him as Akechi Mitsuhide, who they say started a new life as a monk after losing the Battle of Yamazaki. (Look it up though, very significant battle.)
Chihaya Station is a train station along the JR Kagoshima Line, between Kokura and Fukuoka.
The Chihaya was also an old cruiser active in the very early 1900's.
And to add to the apparent obsession with this name, Chihaya Castle was also a castle in present day Osaka Prefecture. It was besieged in 1333, in a power struggle against the Emperor and the Hojo clan. It currently does not exist, but you can at least go up Mount Kongou, which it was built on.
The Haruka (no kanji, just hiragana) is a train line running from Maibara Station, all the way out to Kansai International.
Yayoi (with the kanji 弥生) is a time period in Japanese history (from 300 BC to 300 AD), the traditional name for March, and a Mutsuki-class destroyer active in the early half of the 1900's which was sunk in World War II by American forces.
The Kisaragi was also a Mutsuki-class destroyer, named after the traditional name for February. Also sunk by American forces in World War II.
The Akidzuki was yet another destroyer that served after the Yayoi and Kisaragi. Unsurprisingly, it was an Akidzuki-class destroyer. Sunk in the Pacific Theater, World War II.
Shijou Station is a local train station in Kyoto, as a stop on the Karasuma Line on the Kyoto Subway. There is also a Gion-Shijou Station in the same city, on the Keihan Line.
Shijou is also the name of an emperor of Japan.
The Hibiki was a Fubuki-class destroyer active during World War II. It was surrendered to Russia after Japan's loss, and ultimately scrapped after some years of service.
Hagiwara Station is a lonely little station out in Ichinomiya, Aichi Prefecture. There's another run by a private train line in Kita-Kyuushuu, Fukuoka Prefecture, and a Hida-Hagiwara Station in on the JR Takayama Line in Gero, Gifu Prefecture.
Minase Station... spelled a little differently (水無瀬, with an extra kanji in the middle) is a train stop between Kyoto and Shin-Osaka Stations along the Hankyu Kyoto Line.