Even Sakuya can't take flirting Patchy in stride. I love this confident, cool manner on her.

I don't know why she's building a wall.

Hellbus said:

I don't know why she's building a wall.

I think it's shipping. Look at the star in Koakuma's left eye in that last panel.

Could someone translate what the little sign next to the wall says? I still don't get what's going on in the last panel.

It's a tower, not a wall. Same as the one Sakuya is holding on the first page.

Explanation courtesy of glasnost:

The joke is kimashita waa vs. kimashi tawaa. "Kimashita waa" would be the polite version of "kitaaaa" and is used when you are excited by yuri. But it sounds like kimashi tawaa, or kimashi tower.

An English analogy would be something like Koakuma constructing a ship (and Sakuya also holding a model ship on the first page).

The sign might say "kimashi tower planned construction site", but he can't be certain on mobile.

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