Two Rinkai lines

If you have been on a train in Tokyo, you might have heard of Rinkai line at least once. JR East's onboard English announcement calls it "Tokyo Rinkai Kosoku Tetsudo Rinkai Line", which is merely a transliteration of the official Japanese name. This is frankly absurd, as there is an official English name, Tokyo Waterfront Railway. Anyway, there is a railway called Rinkai Line.

However, there is another Rinkai line in Tokyo, which is officially called Tokyo Rinkai Shin-Kotsu Rinkai Line. Aren't they the same? No, they aren't. Are they operated by the same company? No, they aren't. Do they serve the same area? Yes, they do. What a confusing story it is!

Tokyo Waterfront Railway Rinkai Line – which I would call it the "genuine Rinkai Line" - is, however, not registered on public documents. Its official name is "Rinkai Fukutoshin Line" (lit. Waterfront Subcentre Line). The line was called as such when it opened in 1996, but it has been called Rinkai Line since 2000 (otherwise it must be extremely confusing especially after Tokyo Metro Fukutoshin Line was opened in 2008). Rinkai Line connects Osaki (an interchange station with JR Yamanote Line) and Shin-Kiba (an interchange station with JR Keiyo and Tokyo Metro Yurakucho lines). As the word "waterfront" suggests, trains run newly developed areas very close to Tokyo Bay.

More than 99% of the entire population have never heard of Tokyo Rinkai Shin-Kotsu Rinkai Line (lit. "Tokyo Waterfront New Transit Rinkai Line"), but not a few people know its nickname: Yurikamome. It is an automated guided transit, perhaps the most famous one in Japan. Yurikamome opened in 1995, about five months earlier than TWR Rinkai Line (the "genuine" one). Today, Yurikamome connects Shimbashi and Toyosu, and many foreign tourists have also visited the area before the pandemic.

Are these two lines lie closely? They do. Yurikamome steps across TWR Rinkai Line twice near Daiba and Ariake stations. They run parallel for nearly a mile, though they cannot see each other as TWR Rinkai Line is mostly underground. Ariake station on Yurikamome and Kokusai-tenjijo station on TWR Rinkai Line are the closest interchange, as there are less than 300 yards.

Finally, isn't there a risk of confusion. Mostly no, as 999 out of 1,000 people would not call Yurikamome's official name. In most cases, "Rinkai Line" refers to TWR, not the automated guided transit.