1: kmullin (1100) 2017-01-29 19:01

After your move 23, i actually had a mate. Well, i didn't see it.

Basically, the mate shape is this:

http://sfenreader.appspot.com/sfen?sfen=3gk4%2F7%2BR1%2F3ppp3%2F9%2F9%2F9%2F9%2F9%2F9%20b%20GSr2b2g3s4n4l15p%201

9 手 moves.

So, it seems like 19 ☗３六飛 (R-3f) is dangerous.

The most common response at that point seems to be ☗８七歩 (P*8g): http://kyokumen.jp/positions/2554410

So, 横歩取り急戦☖３三角 B*3c Rapid Attack Side Pawn Capture interestingly differs from regular 横歩取り☖３三角 B-3c Side Pawn.

2: hanton (1343) ☗1☗2☗92017-02-05 10:59

Thinking back now, 22手目 is threatmate. 
I thought this position was dangerous, but not threatmate.
 
Thank you for your advice!