Tony : May I come in - Gomen kudasai
Kobayashi : Yes, who is that? - Hai, Dochira sama desu ka?
Tony : I’m Tony - Toni desu.

Kobayashi : Oh, Tony, welcome. Please come in - Maa, Toni-san, irasshaimase. Dōzo oagari kudasai.
Tony : Sorry for disturbing - Hai, ojama shimasu

John : Please (go in first) - Osaki ni dōzo
Tony : Thanks - Dōmo

Tony : Excuse me - Shitsurei shimasu
John : Excuse me - Shitsurei shimasu

Kobayashi : Please take a seat - Dōzo okake kudasai
Tony : Thank you - Hai, arigatō gozaimasu

Tony : This is John from America - Kochira wa amerika kara no Jon-san desu
John : I’m John, nice to meet you. - Hajimemashite. Jon desu
Kobayashi : I’m Kobayashi, nice to meet you. Regards - Kobayashi desu. Hajimemashite. Dōzo yoroshiku.

Meaning : Gomen Kudasai (May I come in), Dochira Sama (Who - polite form), Irrashaimase (Welcome), Oagari (Rise, Come In - polite form), Ojama (Disturb), Osaki (First), Dōzo (Please), Dōmo (Thanks), Shitsurei (Excuse), Okake (Sit Down), Kochira (This), Kochira (This - for human - polite form), Hajimemashite (Nice to meet you), Yoroshiku (This is something like “All the best” or asking someone for a favor)