YOU SAID:

Hooray, he's coming up the stairs

INTO JAPANESE

やあ、彼は階段を上っている

BACK INTO ENGLISH

Hi he is going up the stairs

INTO JAPANESE

こんにちは、彼は階段を上っていきます

BACK INTO ENGLISH

Hello, he will continue up the stairs

INTO JAPANESE

こんにちは、彼は階段を上がり続けます

BACK INTO ENGLISH

Hello, he will continue to rise the stairs

INTO JAPANESE

こんにちは、彼は階段を上がり続けます

BACK INTO ENGLISH

Hello, he will continue to rise the stairs