"I look up -- and on the pure white of Mount Fuji’s lofty peak the snow continues to fall"

Uta Koi episode 5 was another double-barreled one -- the poem Kisen recited also being from Hyakunin Isshu, #8. Though of course the bulk (call it 5 part a) was Komachi's story.

Which takes place in the early spring of 860, in the aftermath of episode 1a -- over a decade after episode 4, with Narihira going on 35. That Narihira traveled to Mikawa Province (modern Aichi Prefecture) is attested in attested in KKS #411-412 -- the irises were a visual reference to that first poem. The date of Yasuhide's appointment as secretary of Mikawa, attested from Komachi's response is to his invitation in KKS #938 (the one he rightly had so much trouble interpreting), is unknown but 860 is consistent with his known career. Combining the two trips is good plotting. Taking along Komachi, of all people, is just whack. I love talespinning like that.

Other references: The Fuji poem Komachi goes "otaku" over is another HI poem, #4. Narihira's moon-viewing comments plays off another famous KKS poem of his. I didn't catch the poem Komachi recites at the start, and haven't rewatched yet.

Confession time: ( I guessed wrong about Komachi's poem )