I'm a native Japanese speaker. I hope you will call me whenever you want to talk in Japanese or English(a language you are studying) and you let me do the same. I think 30 mins would be enough. if we can talk for 30 mins 3 or 4 times a week, for example, our skill must be improved! I like reading books about language, politics, history, philosophy and religion. I always seek a way to learn efficiently. I love something systematized. Feel free to send me a message even if you dont study Japanese or you are a japanese! I use LINE, Skype and Whatsapp. in JST, at 8:30 9:00 12:00 13:00 16:00 17:00 i think i have time.