Boston went from widespread ramen indifference to underserved ramen mania to a plethora of ramen options in a few years. Ganko Ittetsu Ramen, a newcomer tucked in Coolidge Corner’s Arcade Building, serves three types of Sapporo-style ramen. The star is miso ramen with a luscious, translucent broth, really good noodles, fatty pork belly and a fabulous five-minute egg. Craft beers and ciders are a welcome new addition. Ganko Ittetsu is a jewel in Boston’s now-gaudy ramen crown.