Many houses/apartment offer free internet services but if your house does not offer it then you can talk about it with the house owner or you need to visit shops that provide internet services. The ma...in internet line providers are NTT, au KDDI (au Hikari) and Softbank. here are their official websites in English :
1)NTT East (English): NTT East Official Site for Internet Connection Services https://flets.com/english/
2)au Hikari (English): au Hikari Official Site for Home Internet Connection https://www.au.com/english/internet/
3)Softbank (English): Softbank Hikari Official site for Home Internet Connection https://www.softbank.jp/en/internet/