A mochi making competition for New Years. That could be interesting.

What are they looking at?

Steak said:

What are they looking at?

Well, either they might be getting larger, or that she had the pins on the other side before.

It looks like they used to be buttons, the buttons popped off because Tawawa, and so they're being held together by safety pins, and the safety pins seem to be tearing through the shirt fabric as "the girls struggle to get free".

NWSiaCB said:

It looks like they used to be buttons, the buttons popped off because Tawawa, and so they're being held together by safety pins, and the safety pins seem to be tearing through the shirt fabric as "the girls struggle to get free".

They were always held by safety pins. Her top used to be folded right over left as is done for a corpse at a funeral. I think she switched since this invites unwanted attention.

micsolice said:

They were always held by safety pins. Her top used to be folded right over left as is done for a corpse at a funeral. I think she switched since this invites unwanted attention.

That is a lot of stress on that fabric, look at those tear lines.

micsolice said:

They were always held by safety pins. Her top used to be folded right over left as is done for a corpse at a funeral. I think she switched since this invites unwanted attention.

Which actually explains a detail - the holes in the fabric on her left side were made by the safety pins when the top was folded the other way.

Steak said:

What are they looking at?

Ai-chan Jitome-chan and Ai-chan's sister? I think Ai-chan Jitome-chan is poking the boobies (you can see the motion lines), so I think that's part of a "mochi pounding" joke (with Sada-chan's boobs being the mochi).

(Edit: Thanks for the tip. It's hard to tell Jitome's jitome when it makes sense as a normal expression, but the hairclip seals the deal.)

Is Sada-chan going to become the shrine's god? Is she building up faith in those mountains?

Mithiwithi said:

Which actually explains a detail - the holes in the fabric on her left side were made by the safety pins when the top was folded the other way.

Ai-chan and her sister? I think Ai-chan is poking the boobies (you can see the motion lines), so I think that's part of a "mochi pounding" joke (with Sada-chan's boobs being the mochi).

Ai-chan's sister in in the background with Volley-bu-chan, pounding mochi. The other girl "pounding" Sada-chan's "mochi" is Jitome-chan, her nickname referring to her eyes.

schoolfreak32 said:

Ai-chan's sister in in the background with Volley-bu-chan, pounding mochi. The other girl "pounding" Sada-chan's "mochi" is Jitome-chan, her nickname referring to her eyes.

That's Jitome-chan, Ai-chan's sister is poking Sada-chans breasts with Ai-chan, look at the hair and height.

cd_young said:

That's Jitome-chan, Ai-chan's sister is poking Sada-chans breasts with Ai-chan, look at the hair and height.

Ai-chan is pounding the mochi with Volleybu-chan.
Ai's imouto is the one poking Sada-chan's breasts with Jitome-chan, just look at her hairstyle and mainly, the eyes. Plus Himura's comment on the pic hints that.

Steak said:

Is Sada-chan going to become the shrine's god? Is she building up faith in those mountains?

There already is a god, as revealed in the comiket compilations. They’re a horny perv and ship Jitome-chan and her love interest.

Added the rest of the commentaries for translation.