Go Soeda rallied from a set down to defeat Alejandro Falla 4-6, 6-4, 6-3, 6-3 on Sunday as Japan earned a berth in the Davis Cup World Group with a 3-2 win Colombia.
Colombia went into Sunday's reverse singles with a 2-1 lead over the hosts but Kei Nishikori made it 2-2 with a 6-1, 6-2, 6-4 win over Santiago Giraldo in the first match.
Giraldo had 61 unforced errors to Nishikori's 31 in the match at Ariake Colosseum.
The victory booked Japan's return to the top flight after a one-year absence. Colombia was trying to earn a spot in the World Group for the first time.