The solar-powered rovers' voltage plunged as night fell on Ryugu, a sign that they are on the asteroid, said Hayabusa project team spokesman Takashi Kubota.
The agency said the robots - round and biscuit tin-shaped - are the world's first man-made objects to explore movement on an asteroid's surface.
An artist impression from the by the Japan Aerospace Exploration Agency showing the rovers landing on the asteroid.
Measuring just 18-by-7cms and weighing about one kilo, MINERVA-II1 rovers will take advantage of Ryugu's low gravity to hop about the surface of the asteroid, which is approximately one kilometer in diameter.
So far so good, but JAXA must still wait for Hayabusa2 to send the rovers' data to Earth in a day or two to determine whether the release of the probes succeeded, officials said.
"I'm proud we now have the means to travel across the surface of a small astronomical body, and that Hayabusa2 was able to contribute", project manager Yuichi Tsuda said in a written comment.
The cautious announcement came after a similar JAXA probe in 2005 released a rover that failed to reach its target asteroid.
The first image was taken after the separation of the two cylinder-shaped explorers from the Hayabusa2 space probe.
The spacecraft is set to release a German-French lander called MASCOT carrying four observation devices in early October and a bigger rover called Minerva-II-2 next year.
From this crater, the probe will collect "fresh" materials unexposed to millennia of wind and radiation, hoping for answers to some fundamental questions about life and the universe, including whether elements from space helped give rise to life on Earth. The robots will take photos and temperature readings of Ryugu before Hayabusa2 space probe lands on the asteroid's surface in 2019.
The main Hayabusa 2 vessel should near the surface in October, when it will shoot a tantalum "bullet" into the asteroid so that it can catch particle samples and return them to Earth.