Tested everything over multiple trips to tokyo. Heres what delivers reliable connectivity:

tourist sim cards: iijmio at narita airport counters ¥1500/7 days with 6gb data. Works perfectly on docomo network across yamanote line and metro

pocket wifi rental: narita/haneda airport counters ¥500/day unlimited data multiple devices. Heavy to carry but reliable coverage in tokyo subway tunnels

free wifi reality: starbucks shibuya and mcdonalds harajuku have decent free wifi. Konbini 7-eleven wifi needs japanese phone number verification - useless for tourists

recommendation: tourist sim for google maps navigation plus jr east station wifi spots. Download tokyo offline maps before arriving. Skip softbank international roaming ¥1000+/day for worse service