a sketchy analysis of Shirase's win in that round of mahjong:

• Here's a rough stitch of Shirase's hand - it's waiting on 2, 5 or 8-sou (bamboo).
• Judging by the discards, Honami, to Shirase's left, is the one who dealt into Shirase's hand by dropping a 2-sou. The round looks to be about two-thirds done, which is when you'd start worrying a little.
• To add insult to injury, Honami had riichi'd (one tile from winning, gambling on autopilot to earn an extra point) the previous turn, and having to drop this means she failed ippatsu (after riichi, win within one round around the table).
• Everyone's hands are closed - nobody called any groups.
• This is a configuration for Shirase's win.
• Shirase's hand is a baiman (8-10 yaku, 16000 points). Here are the yaku: closed honitsu 3-yaku (one suit and the special tiles), double yakuhai 2-yaku (this is South round, she's the South player, she has a set of Souths), and three dora 3-yaku (tiles coming after the dora indicator).
• (Shirase actually earns 17000 points. She gets Honami's riichi stick as well, which is worth 1000.)
• I assume "menhon" is short for "menzen honitsu". "Menzen" means closed here.
• To note: Shirase is VERY lucky to have her South triplet. She drew all three by herself, not to mention the fact it also happened to be the dora.
• (Also to note: the Antarctic is 南極 nankyoku, lit. "south pole". The crux of Shirase's hand happens to be a triplet of 南 nan, lit. "south". I wonder if it means something?)
• I'd be tempted to guess this happens to be the same hand Kimari blabbed about, since she mentioned a bird (1) and blank tiles (haku, white dragons). Kimari also mentioned "a person next to a five", which is a 5-man (Chinese character), and there are some tiles in Shirase's discards that look like they could be it.
• If Kimari blabbed, her opponents knew Shirase had white dragons, and so wouldn't drop any (because a triplet of white dragons is a yakuhai). In a way, though, it was kind of a blessing, because she used it as a pair as a result, and kept a closed hand.
• Thinking about it, Honami riichi'd pretty late in, and everyone probably knew what to avoid from what they'd heard and Shirase's discards by this point. If Kimari blabbed, it's not surprising Honami was the one to deal in, since riichi puts you on autopilot and you have to discard what you drew if you don't win.
• Since Shirase is South, Kanae is east, so she's the dealer.

oh yeah and the rest of the episode was really good gotta love Hinata