The real reason why Kazuya from Rental Girlfriend was renting one...

One of the first few Japanese phrases you'll learn is "いくらですか？"

Bespoke: Make your own LLM girlfriend speak in Japanese and learn it from her. Then you won't have to worry about getting scammed, you'll have the almost-perfect companion... and join the ranks of r/waifuism.

Source: "How to get better at Japanese" by Dogen