Kunitachi (国立) is a city in Tokyo prefecture. The naming of Kunitachi comes from its location: sandwiched between Kokubunji City (国分寺) and Tachikawa City (立川), the first kanji in each city was combined, making it Kunitachi (国立). Kunitachi is known for its posh, high class neighborhood, and for its many schools. There are many public and private schools and two universities (Hitotsubashi University and Kunitachi Music University). This city is often used as a location where Japanese TV drama shooting is taken place. Examples such as "Antique(2002)" which stars Hideaki Takizawa as a patissier, "H2(2005)" drama version for the famous Japanese comic, and more...
Kunitachi has 3 train stations. Kunitachi Station of JR Chuo Line, Yaho (谷保) and Yagawa (矢川) Station of JR Nambu Line. From Shinjuku, you can take the JR Chuo line to Kunitachi Station (about 35 minutes. if on the express train, change to local train at Kokubunji Station). You can also take Keio Line from Shinjuku to Bubaigawara, then change to JR Nambu Line (towards Tachikawa direction) for Yaho Station (The trip costs 400 yen and about 25 minutes).
You can travel to Shibuya quite easily as well, travel on the JR Chuo Line to Shinjuku and change onto the Yamanote Line (around 50 minutes for 450 yen) or change at Kichijoji onto the Inokashira Line (Keio) to Shibuya. This option will take a little longer but is cheaper at 400yen. Also there is a higher chance to get a seat because the Chuo Line and the Yamanote Line are two of the most frequented train lines.
It's not a big city, so walking around is the best. Take the South Exit of Kunitachi Station, and explore Daigaku dori (University Avenue).
Kunitachi is famous for its cherry blossoms in late March to early April. Daigaku Dori (University Avenue) that runs southward from Kunitachi station and Sakura Dori (Cherry blossom Avenue) that runs East-West makes an excellent stroll.
Kunitachi has few hotels. You had better use a hotel in Tachikawa. (By a train 4 minutes.)