Ask her if she morphs into your Japanese Mom.

"So um... 'mom', I don't know if you could, um... can you morphs yourself into the Japanese mom again, like you did before when we have sex?" you asks awkwardly.

"Of course, sweetie. There's always the thing 'mommy' can do for her 'son'." your shapeshifting girlfriend/mom answers as you looked at your girlfriend/mom as she quickly starts shrinking down a bit and changing her racial appearance into Japanese. First, her face has less wrinkles and making her way more younger than 'herself', as for her hair getting longer and become black. And then, the skin of her body are changing her new color. After that, her breasts which are double size of F-cups are stay the same, but her nipples are getting bigger. Finally, when the transformation is complete, your transformed girlfriend/mom has now become a Japanese mom like one of your hentai anime MILF. "Soo, you like?" she asks with her cute Japanese voice and accent.

"Yes, 'mom'. I do." you blush.

"Teehee, you so red." your girlfriend/mother asks.

"Be...because I... well... you look so beautiful when you're younger, 'mom'." you answer awkwardly as your girlfriend/mom giggles.

"Ara Ara, ありがとうございました." your shapeshifting girlfriend/mom says as she admires you when you said she's beautiful."And y'know, if you want me to be into someone, you could ask 'ママ', because I do this for my cutiepie."

"Thank, 'mom'... I mean Kaa-san." you finish your word as you then give her a kiss on the lips.

"Anyway, what now?" your Japanese shapeshifting girlfriend/mom asks when she broke the kiss.