Welcome aboard the WMR service to Wellington! Last stop Linton, next stop Makerua.
The first building in Tokomaru township, as with many other towns along this route, was the railway station, built in 1886. A goods shed, cattle yard and a longer siding were installed in 1892. These were extended in 1907, just before the government buyout in 1908. In 1911 the station was upgraded with a ladies waiting room. Tokomaru Station was finally demolished in 1972 and now the only thing remaining is a small goods shed.
Tokomaru township is named after the local Māori leader Ihakara Tukumaru. Tukumaru was highly regarded as a peacemaker and had also sold land to the government - he sold 240,000 acres in this area in 1866 and another another 37,000 acres near Foxton eight years earlier. The town itself is an example of a large parcel of land bought by the railway and sold off specifically to be a town, one of the primary methods that the WMR used to raise funds to pay off its loan. The first lots were sold by auction on 24 June, 1887, making this the date that Tokomaru township was born.
You can read an excellent history of Tukumaru at the Foxton multi-cache GC5Q2A4: Ihakara Tukumaru (Matakarapa).
Tokomaru also sports its own Steam Engine Museum, with a kilometre of track.

Tokomaru Station, about 1908
Standing on/crossing the rails is illegal, unnecessary and likely to get you run over. Don't do it. Tracks are for trains!
References:
Cassells, K.R.: "Uncommon Carrier", published by the New Zealand Railway and Locomotive Society, 1993.
The New Zealand Railways Magazine, 1 January 1936: "Tokomaru"
ArchivesCentral: "The Wellington & Manawatu Railway Company Limited: Plan of the township of Tokomaru and suburban land"
Horowhenua Kete: "Horowhenua Railway Stations"