Is multi-day transit possible for Japan

Hi,
I'm a Vietnamese citizen with Vietnamese passport.
In March 2018, I have a business trip to USA, and have acquired B1 visa for it.
On my flight back (from New York to Saigon), I intend to take transit in Tokyo, and apply for transit visa to be able to leave the Narita airport and visit Tokyo.
Consulate website said that a transit visa is up to 15 days.
I want to ask if I can purposedly book two connecting flights with 3-4 days in between.
(For example: From a same airline, ANA, book a flight from New York to Tokyo, then 3-4 days later from Tokyo to Saigon).
Will it still be considering as transit, or do I have to apply for standard visit visa

Any helpful reply will be more than appreciated, thanks.

If you wanas go through immigration, then you need a visa. Transit time or number of days is irrelevant.

Arigatou, Hakata-san!

I'll apply for a transit visa then.

Transit (Up to 15 days)
(Note; if you intend to see friends or stay with friends while in Japan you should apply for a Temporary Visitor Visa, not a Transit Visa; a double transit visa is possible; please contact the Embassy for further details)