The Sunwolves came crashing back to earth two weeks after their first Super Rugby victory with a 40-22 loss to Australia's Western Force on Saturday.
Akihito Yamada scored a try in the fourth minute to give the Sunwolves hope of following up their historic win over the Jaguares with another victory against the struggling Force at Prince Chichibu Memorial Ground.
But a quick-fire hat trick by Force winger Marcel Brache and a try by Brynard Stander staked the visitors to a 26-5 halftime lead, and second-half tries by Tusi Pisi, Derek Carpenter and another for Yamada were not enough to haul the Sunwolves back into contention.
"One of the things we were most disappointed in looking back was our energy in the first half," said Sunwolves head coach Mark Hammett. "I don't believe we were tired but collectively if we don't bring the energy together, it's hard to achieve the style that we want.
"The reserves changed the pace of the game. Then we started playing Sunwolves rugby and really attacked well."
The Sunwolves had two weeks to prepare for Saturday's game with a bye week following their maiden win over Argentina's Jaguares, but instead it was the Force who came out with all guns blazing.
"We managed to score early but we couldn't keep it up," said Sunwolves captain Shota Horie. "We weren't able to get into our rhythm early in the game. I think mentally our lack of experience also played a part."
An explosive start by the Sunwolves saw Yamada cross the line for his sixth try of the season. A fast-passing break saw Horie pick out Carpenter, and the New Zealander punched a hole in the visitors' defense before sending Yamada over for the score.
"Carpenter made the breakthrough and I thought he would pass so I stayed up in support of him," said Yamada, who was returning from a two-game injury layoff.
"I haven't been able to score when we've played in Tokyo so it was nice to get two tries today. But I want my tries to help the team win."
The Sunwolves' lead, however, lasted just two minutes. Harumichi Tatekawa attempted an ill-advised pass deep inside his own team's territory, and Brache easily picked it off before darting over the line.
Brache sunk the Sunwolves into a deeper hole with his second try of the game in the 13th minute, before the winger took advantage of some slack tackling to complete his hat trick midway through the first half.
Stander added another try in the 27th minute, and luck appeared to have completely deserted the Sunwolves when fullback Riaan Viljoen crossed the line only for a Force defender to knock the ball out of his hands at the crucial last moment.
Things got no better in the second half when Ben McCalman crossed the line to extend the visitors' lead in the 52nd minute, but flyhalf Pisi gave the Sunwolves a glimmer of hope when he charged over for a try six minutes later.
Carpenter further reduced the arrears with a try in the 70th minute, but Force substitute Angus Cottrell crossed the line four minutes later to make Yamada's 79th-minute try a mere consolation.
"It's a good reality check of the competition we are playing in," said Hammett. "We are obviously all very happy with the win over the Jaguares but in a way that puts a target on our heads now. For us to grow and improve, we need to embrace that challenge week in and week out."
The Sunwolves' next game is against the Stormers in Singapore next Saturday, with their final fixture in Tokyo against the Waratahs on July 2.