Hokusō Line

• Hokuso 7300 series (since 1991)
• Hokuso 7500 series (since 2006)

• 
  Hokuso 7300 series

• Chiba New Town Railway 9100 series (since 1994, branded "C-Flyer")
• Chiba New Town Railway 9200 series (since March 2013)
• Chiba New Town Railway 9800 series (since 21 March 2017)[1]

• 
  Chiba New Town Railway 9100 series
• 
  Chiba New Town Railway 9200 series
• 
  Chiba New Town Railway 9800 series

• Keisei 3000 series (since 2003)
• Keisei 3050 series (since 2010)
• Keisei 3100 series (since 2019)
• Keisei 3400 series (since 1993)
• Keisei 3500 series (refurbished sets only)
• Keisei 3700 series (since 1991)
• Keisei AE series (since 2010)

• Keikyu 600 series (since 1994)
• Keikyu N1000 series (since 2002)
• Keikyu 1500 series (since 1985)

• Toei 5300 series (since 1991, through service with Toei Asakusa Line)
• Toei 5500 series (since 2018, through service with Toei Asakusa Line)

• Chiba New Town Railway 9000 series (from 1984 until 20 March 2017)[1]

• 7000 series (from 1979 until 2007)
• 7050 series (rebadged Keisei 3150 series cars leased from Keisei)
• 7150 series (from 1991 until 1998, converted from former Keikyu 1000 series EMUs)
• 7250 series (from 2003 until 2006, converted from former Keisei 3150 series EMUs)
• Hokuso 7260 series (from 2006 until March 2015, converted from Keisei 3300 series EMUs)

• 
  Chiba New Town Railway 9000 series in August 2007
• 
  7150 series in July 1995
• 
  7250 series in February 2006
• 
  Hokuso 7260 series in August 2007

• 800 series (also leased to Hokuso Railway)
• 8800 series
• 8900 series
• Keisei 200 series

• 3050 series (original) (until 1995)
• 3100 series (until 1998)
• 3150 series
• 3200 series (until 2007)
• 3300 series (unrefurbished sets)
• 3500 series (unrefurbished sets)
• 3600 series

• 5000 series
• 5200 series

• Keikyu 1000 series (until 2010)

This section was planned as a railway access to Chiba New Town. Initially proposed by a committee of the then Ministry of Transport, the route was numbered "Line 1", as the northern extension of Tokyo Metropolitan Bureau of Transportation (Toei) Line 1 (present Asakusa Line) to Komuro area of Chiba New Town. In 1979 the first phase of this section between Kita-Hatsutomi and Komuro opened. The through-operation via Shin-Keisei Line to Matsudo began, on a temporary basis until the second phase of this section could connect the town directly to the Keisei and Asakusa Line network.

The second phase section to Keisei-Takasago on the Keisei Main Line opened in 1991, and through-operation began. In the following year, Shin-Keisei included Shin-Kamagaya Station as a transfer station, and abandoned the temporary route.

The section east of Komuro was initially the eastern part of a once-planned Chiba Prefectural Railway (千葉県営鉄道, Chiba Ken'ei Tetsudō) (II, apart from the first which opened the Tōbu Noda Line and the Kururi Line) as an extension of Line 10 (Shinjuku Line). The line was to be built from Moto-Yawata via Komuro to parallel to the line above, then to terminate at present Inba-Nihon-Idai. The first section between Komuro and Chiba New Town Chūō was opened in 1984, and the operations were commissioned to the present Hokusō Railway.

• March 9, 1979: Hokusō Line (first phase) of Hokusō Development Railway (北総開発鉄道, Hokusō Kaihatsu Tetsudō) Kita-Hatsutomi – Komuro. Through-operation via Shin-Keisei Line to Matsudo on temporary basis.
• March 19, 1984: Chiba New Town Line (千葉ニュータウン線, Chiba Nyūtaun sen) of Housing and Urban Development Corporation (住宅・都市整備公団, Jūtaku Toshi Seibi Kōdan) (HUDC onwards) Komuro – Chiba New Town Chūō
• April 1, 1987: On the section of Komuro – Chiba New Town Chūō, Hokusō Development Railway became the Category-2 Railway Business operator, while HUDC became Category-3 Railway Business. On the commencement of the Railway Business Act (鉄道事業法, Tetsudō Jigyō Hō), Act No. 92 of 1986) for the privatization of the Japan National Railways. Simultaneously, the entire stretch was renamed to Hokusō Kōdan Line (北総・公団線, lit. Hokusō and the Corporation Line)
• March 31, 1991: Hokusō Line (phase 2) Keisei-Takasago – Shin-Kamagaya. Through-operations by four parties (Hokusō, Keisei Electric Railway, Tokyo Metropolitan Bureau of Transportation (Toei), Keihin Electric Express Railway (Keikyū)) began.
• July 4, 1992: Shin-Keisei opened Shin-Kamagaya Station. Through-operation to Shin-Keisei terminated. The section of Kita-Hatsutomi – Shin-Kamagaya was abandoned.
• April 1, 1995: Chiba New Town Chūō – Inzai-Makinohara, as Hokusō Cat-2, HUDC Cat-3
• 1999: HUDC reorganized to the Urban Development Corporation (都市基盤整備公団, Toshi Kiban Seibi Kōdan) (HDC onwards), continued state of Cat-3 of the line.
• July 22, 2000: Inzai-Makinohara – Inba-Nihon-Idai, as Hokusō Cat-2, HDC Cat-3. Present stretch completed.
• July 1, 2004: Railway properties of HDC transferred to Chiba New Town Railway (千葉ニュータウン鉄道, Chiba Nyūtaun Tetsudō), and the whole line was renamed as the Hokusō Line.

After the abandonment of the planned Narita Shinkansen, routes of rapid transit to Narita Airport had long been discussed. For a utilization of partially completed tracks of the Shinkansen, JR East and Keisei lines to Narita Airport were realized. A much faster line had long been needed, and for that purpose the first priority was the Keisei – Hokusō route. In 2001, a new Cat-3 entity, Narita Rapid Rail Access (成田高速鉄道アクセス, Narita Kōsoku Tetsudō Access) commenced building a new line connecting Inba-Nihon-Idai to the junction to Narita Airport Rapid Railway (成田空港高速鉄道, Narita Kūkō Kōsoku Tetsudō) which is a Cat-3 company of existing access railways, the tracks of the formerly planned Narita Shinkansen. The express trains are operated by Keisei as a Cat-2 operator with maximum speed at 160 kilometres per hour (99 mph), the fastest in Japanese private railway together with Hokuetsu Express, which enables a 34-minute journey from Nippori to Narita Airport. The line opened in July 2010.

Hokuso Railway fares are significantly higher than those of other private railways in the region. A journey of 12.7 km on the Hokuso Line costs 540 yen, while a 23.8 km journey costs 720 yen. Equivalent journeys on the Keisei Main Line cost 250 yen and 360 yen respectively; equivalent journeys on JR cost 210 yen and 380 yen respectively. The difference in fares is largely due to the debt burden remaining from the portion of the line built and owned by Hokuso Railway itself; this is also the case for the Tōyō Rapid Railway Line and the Saitama Rapid Railway Line, which are also known for having comparatively high fares.[2]

In 2009, Chiba Prefecture and several municipalities along the line agreed with Hokuso Railway for an average fare reduction of 4.6% (25% for student commuter passes), in exchange for which they agreed to subsidize half of the estimated revenue loss of 600 million yen. The fare reduction was implemented in July 2010 at the time of the opening of the Narita Sky Access Line. In 2011 and 2012, the cities of Shiroi and Inzai elected new mayors on platforms of negotiating for further fare reductions and stopping public subsidies respectively; a third-party study commissioned by the two city governments concluded in August 2013 that the Hokusō Line would break at even more discounted fare levels without local subsidies. Hokuso, on the other hand, has argued that increased consumption tax rates and capital expenditures related to upgrading the Pasmo system will force them to raise fares in 2015.[3][4]