Welcome to "How the hell do I play Riichi Mahjong?"

"How the hell do I play Riichi Mahjong?" is a fairly barebones introduction to Riichi Mahjong, because getting sent a 150-page PDF as an """introduction""" to the game by your """friend""" who just """wants to have a friendly game""" can be terrifying and downright dissuasive.

Generally speaking, the best order to read through these pages would be top to bottom as linked on the side, but all pages are linked on every page just in case you need to go back for something else. Also of note is that you can probably count the number of people you know in real life that actually play mahjong of any form on one hand, so I would heavily recommend picking up a virtual simulator of Riichi Mahjong. The only problem, of course, is that when you go and type in "mahjong" basically every storefront assumes you mean Mahjong Solitaire, which is the matching game for 3 and up. To lightly remedy this, here are a few personal picks:
Mahjong Soul, free and browser-based, on iOS and Android as well.
Mahjong Nagomi, on Steam for Windows: USD$4.99
Tenhou, also free and browser-based, but you need a hard-to-setup plugin if you want it in english.
Noten Riichi Mahjong, free for Android. SINGLEPLAYER ONLY, but it has a fairly good built-in guide. Would recommend as an isolated environment to learn the game in.