“Please and thank you” is just not commonly used
The closest English translation that I can think of for yoroshiku-onegaishimasu is the expression used by Ron Swanson’s character in the American TV series, Parks and Recreation, “Please and thank you.”
Naturally, there is more to it than that.
Yoroshiku-onegaishimasu (pronounced yo-ro-she-ku — oh-neh-guy-she-mäs)
Yoroshiku-onegaishimasu is used when you first meet a person. It expresses “please and thank you” for any and all future give-and-take interactions, and it is accompanied with a bow. There is the understanding that one will inevitably ask a favor of the other and vice versa. It’s akin to saying, “May all our interactions be harmonious.”
The other main usage is when asking someone for a favor or for help, when it is a “please — and thank you in advance,” à la Ron Swanson.
In short, yoroshiku-onegaishimasu conveys both a sense of reciprocal gratitude and future thanks.
So, to you, kind readers, for this and all future reading, “Yoroshiku-onegaishimasu!”
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