The Merriam-Webster dictionary defines "senryu" as "a three-line unrhymed Japanese poem structurally similar to haiku, but treating human nature usually in an ironic or satiric vein."
I'm assuming that readers have at least a passing familiarity with haiku, a poetry form best known in the West through the works of 松尾芭蕉 (Matsuo Bashō, 1644-94), whose famous travelogue, titled 奥の細道 (Oku no Hosomichi, "The Narrow Road to the Deep North"), was published posthumously in 1702.
If you happen to be passing through Kawasaki, which borders Tokyo, you can pause before a small stone marker bearing one of Basho's haiku, supposedly on the very spot where he composed it. It's located on the old Tokaido road within sight of Hatcho-nawate Station, one stop on the local train from Keikyu Kawasaki. The haiku reads: 麦の穂を、たよりにつかむ、別れかな (Mugi no ho o/ tayori ni tsukamu/ wakare kana, I clutch the barley ears/ To support myself/ As we have to part ...)