Haijima station is located in Akishima, one of the cities in Tama district of Tokyo. Although Akishima station is considered as the main station of Akishima, Hajima station is the busiest station in Akishima, due to not only JR but also Seibu railway has terminal station of Seibu Hajima line.
JR operates three lines; Ome, Itsukaichi and Hachiko lines. Hajima station is the intermideiate station of both Ome and Hachiko lines but the terminal for Itsukaichi line.
Hajima station is not one of the major stations in Tokyo but it is one of the important stations in Tokyo. There is a direct connection to Shinjuku by JR and Seibu and Tokyo station by JR. You can go to the most populous city in Tama district, Hachioji directly by Hachiko line to Hachioji station. Also to the busiest station in Tama district, Tachikawa station too.
Also has good connection to Saitama prefecture by Hachiko line and Seibu lines. Hachiko line trains continues to run on Kawagoe line which terminates at Kawagoe station. Kawagoe is a major tourist destination in Saitama. Then, from Kawagoe, you can take Saikyo line train to Omiya and change there to Tohoku, Joetsu, Akita, Yamagata and Hokuriku Shinkansen without passing the crowded downtown Tokyo.