Translate Japanese M/S Marking On US Embassy Cvr

Please, would like translation of manuscript marking at left side of cover. Any additional input regarding the postmark, circumstances under which this cover was sent, what it might have contained (Permits?) or about the addressee welcome. Thanks in advance.

The manuscript on the left is "Tokyo Teikoku Hotel", which means " Imperial Hotel, Tokyo", and was written to aid the postman for delivery. The stamps are cancelled at Akasaka PO (Tokyo), received at Marunouchi PO (Tokyo) and then delivered to the addressee. The 6 Sen franking shows that this letter was double weighted (cf. normal domestic letter fee = 3 Sen). There's no further information on the cover though.

- Hironobu

Interesting -

https://en.wikipedia.org/wiki/Caroline_Haven_Ober

unechan, thank you very much for the translation. What's the date of the post mark?