The name comes from romance seats, two-person seats without separating armrests when one-person seats were a norm. Some Romancecars are equipped with standard seats featuring armrests. Other railroad companies also used "romance cars" or "romance seats" (a Japanese portmanteau for "loveseat") for their special accommodation passenger cars, but Odakyu holds the trademark for the term "Romancecar".

Odakyu currently operates the following Romancecar services:

• Hakone and Super Hakone service between Shinjuku and Hakone-Yumoto (on Hakone Tozan Line, terminal station for visiting Hakone mountains and springs)
• Metro Hakone service between Hakone-Yumoto and Kita-senju (in north-east of Tokyo) (direct through service to the Tokyo Metro Chiyoda Line from Yoyogi-Uehara)
• Enoshima service between Shinjuku and Katase-Enoshima (in Fujisawa, Kanagawa)
• Metro Enoshima service between Katase-Enoshima and Kita-senju (direct through service to the Tokyo Metro Chiyoda Line from Yoyogi-Uehara)
• Mt. Fuji service between Shinjuku and Gotemba on JR Central Gotemba Line
• Sagami service between Shinjuku and Odawara (in Odawara, Kanagawa)
• Morning Way trains inbound from Odawara, Katase-Enoshima to Shinjuku until 9:30 a.m.
• Metro Morning Way trains inbound from Hon-Atsugi to Kita-senju (on Tokyo Metro Chiyoda Line)
• Home Way trains outbound from Shinjuku to Hakone-Yumoto, Katase-Enoshima after 6 p.m.
• Metro Home Way trains outbound from Kita-senju (on Tokyo Metro Chiyoda Line) to Hon-Atsugi

These are classified as tokkyū (limited express) services, requiring limited express tickets and seat reservations. Bento meals are available on the train.

• Odakyu 3000 series SE: These pioneering rapid rail trains were introduced in 1957 and were commonly used until 1968; one was used until 1991. They set the world speed record for narrow gauge track in September 1957 at 145 km/h (90 mph) and were an inspiration for the world's first high speed train, the Shinkansen. They later earned Japan's Blue Ribbon design award. The 8-car trains could seat 354 people.
• Odakyu 3100 series NSE: A taller, upgraded version of the 3000 series, it was used from 1963 until 1999. The 3100 series was the longest Romancecar in common service and gave it its distinctive look. The Nagoya Railroad Panorama Car design was based on the 3100 series. The 11-car trainset could seat 464 people, and had a maximum design speed of 170 km/h (106 mph).
• Odakyu 7000 series LSE: Entering service in 1980, it has a 180-degree front view of scenery. It has seating for 464 people in 11 cars—identical to the 3100 series. It was manufactured by Kawasaki Heavy Industries. The two remaining sets were withdrawn from regular service on July 10, 2018, and are scheduled to be operating seasonally until the end of the fiscal year.
• Odakyu 10000 series HiSE: Introduced in 1988, like its predecessor, the 7000 series LSE, these two types are very closely related, and were once the top grade of Romancecar service, but with larger seats than the 7000. Like the LSE and VSE, the driver's compartment is elevated so that passengers at the front of the train have an unimpeded 180 degree view of the scenery. These trains are used for Hakone services, plying the same route as the VSE but stopping more often; the trip to Hakone takes about 90 minutes. Cabin attendants are available for food and drink service, except in the evening. The two remaining sets were withdrawn on March 16, 2012.
• Odakyu 20000 series RSE: Introduced in 1992, and withdrawn in 2012, these trainsets were mainly used for Asagiri services to Gotemba, where they alternated with the very similar JR Central 371 series. They were the only Odakyu trains with first-class seating in "semi-compartments" on the upper deck of two bi-level cars in the center of each train. It was the first in the series to break from the traditional wine red color, being baby blue.
• Odakyu 30000 series EXE: Introduced in 1996, these currently operate most Romancecar services. Most are equipped with vending machines on board, and some also have cabin attendants. They are boxy and metallic bronze in color. From fiscal 2016, sets have undergone a programme of refurbishment; refurbished sets are branded EXEα (Excellent Express Alpha).^[2]
• Odakyu 50000 series VSE: Introduced in 2005, the white VSE featured the driver's compartment elevated over the cabin as with the HiSE. VSE trains were primarily used for Super Hakone services and had cabin attendants who brought food, drinks, and on-board shopping to each passenger's seat during the 80-minute run to Hakone. There were also two cars with cafe spaces, leading to the VSE's reputation as a "moving café" (走る喫茶室). There are seats for 358 people.^[3][4] The two sets were withdrawn from regular service on March 11, 2022,^[5] and were completely retired on December 10, 2023.^[6]
• Odakyu 60000 series MSE: The first Romancecar to be used on through services on the Tokyo Metro Chiyoda Line. Entered service in March 2008.
• Odakyu 70000 series GSE: The newest "Romancecar" model, with an elevated driver's compartment similar to the HiSE and VSE. Entered service in March 2018.^[7]

•  
  3000, 3100 and 7000 series Romancecar trains, left to right, in traditional colors
•  
  10000 series HiSE Romancecar
•  
  20000 series RSE
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  30000 series EXE
•  
  50000 series VSE
•  
  60000 series MSE
•  
  70000 series GSE

• Open Me!, the series finale of Ultra Q, features a flying Odakyu 3100 Series called The Train In The Vary Dimension. It journeys to a pocket dimension with its passengers, a place where those within can be free of the hardships and struggles of daily life, but upon returning, those aboard are left forever insane and unable to go back.
• Romansu (Round Trip Heart), a 2015 Japanese film about a train attendant who works on Romancecar services between Shinjuku and Hakone

• In Vol. 21 of manga Jujutsu Kaisen, the character Kinji Hagari's personal technique of "Sitetsu Junai Ressha" features several station names from Odakyu Odawara Line.

• Yamashita, Kazuyuki (June 1996). "小田急ロマンスカーの足跡" [History of the Odakyu Romancecar]. Japan Railfan Magazine. Vol. 36, no. 422. Japan: Koyusha Co., Ltd. pp. 30–46.

• Limited Express "Romancecar" (Odakyu Electric Railway)