Jane Ayieyam scored for the Black Queens but goals from Mina Tanaka, Mana Iwabuchi, Rika Masuya, Emi Nakajima, Hikari Takagi, Yuika Sugasawa and Aya Sameshima secured a heavy bragging right for Nadeshiko at Transcosmos Stadium in Nagasaki.
The match marked the end of Japan's friendly preparation for the Women’s Asian Cup, which runs between April 6 and 20.
For Ghana, who beat Cote D’Ivoire to lift the recent Wafu Women's Afcon, Sunday's fixture is part of their list of friendlies ahead of hosting the 2018 Women's Africa Cup of Nations in November / December.
Mina Tanaka opened the scoring for Japan in the 14th minute, slotting the ball past goalkeeper Patricia Mantey when Rika Masuya laid a through-ball.
Ayieyam hit back for Ghana in the 25th minute, capitalising on a defensive lapse to slot home a rebound after her header came off the woodwork.
The hosts, however, restored their lead three minutes later through Iwabuchi, who scrambled the ball over the line when Mantey's save from Tanaka's effort fell in her path.
Three minutes to half-time, Japan made it 3-1 as Masuya slammed home from about 12 yards when Nakajima delivered a cross into the box.
There minutes after recess, it was Nakajima's time to shine as she scored to make it 4-0, having been set up by Rin Sumida.
Takagi and substitute Sugasawa then added their names to the score sheet, before Sameshima netted the last goal to ensure a 7-1 win for the hosts.