Unhappy [Q] HELP

Hello, I am new here. I am having some difficulties with my htc one M7. My service is through sprint. I am currently studying abroad in Japan until the end of May. I decided to get a WiFi sim card so that I may still use my device without international charges. I got the sim card through ASAHI Net, asahi - net . jp / en / join / It requires that I add an APN but my phone is not allowing me to add a new APN let alone access the APN. This is a screen shot of what it shows me. I am not technically savvy so I appreciate any help. THANK YOU!!!
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