Les Lucioles du Josas guides runners through Jouy-en-Josas, near Paris, at night, equipped with headlamps and surrounded by town Christmas lights. This is a festive trail race offered in 8 km or 12 km distances, held during the holiday season, connecting the Christmas market with the nearby natural areas.
The course is more challenging than straightforward, featuring climbs, stairs, potential mud from wet weather, and winter conditions like fog or snow. It includes unique sections that distinguish it from a typical road race. Costumes are encouraged, particularly comic book and manga attire, leading to a start line that resembles a night parade more than a standard race. The atmosphere is family-oriented, welcoming both children and adults. The event concludes with seasonal touches like mulled wine and cinnamon scents, with participants lingering afterward.