Illuminations are one of the trademark events of the colder months in Japan, and you'll find a plethora of them to check out across the country, including many in the Tokyo area. The Tachikawa Sansan Illumination is one that's ultra easy to access – it started back in 2004 and includes lights decorating the trees along Sansan Road and around Tachikawa Station's north exit.
The primary purpose of this event is to enhance the region in the lead-up to the Christmas season, with the hopes of promoting a bit of holiday shopping – so if you need to pick up some gifts for loved ones you've got the perfect incentive to do so!