What even is a Harvest Show? One recurring element in Love Kome: We Love Rice is the idea of a "Harvest Show", which is something that Hinohikari (our protagonist) desperately wants to be a part of. I had previously understood this to be some sort of rice-based performance art, judging from what we'd seen of the Hinohikari / Akitakomachi 
/ Nikomaru cross-dressing idol unit. (Yes, if you thought you'd seen everything, come watch Love Kome for an idol unit composed of cross-dressing personified rice varieties.)

However, in episode 5, Sasanishiki stops a bullet train from running over a conveniently-placed dog by means of what onlookers (Hinohikari and friends) describe as a "Harvest Show". (It is unclear how creating a few ears of rice helped anything here, but this is anime, so whatever.)



An insert song (titled "Fine Dress") does play in the background as he leaps from the roof of the school (summoning, in the process, a jelly donut rice ball), but he's not actually singing it in-show.

So basically I no longer have any idea what a Harvest Show is in this anime.
The official site (Japanese) describes it as

Harvest Show
It is a live performance for the grains to appeal for their deliciousness to the surroundings.

which is basically the same as what MAL and ANN describes

[...] to perform at the &quot;Harvest Show&quot; to show the delicious appeal of rice grains.

How or what do they do, don't ask me... but in addition to its comedy genre, the show is full of parodies.

Sasashiniki stopping a bullet train from hitting a dog in episode 5 is actually a parody of Kinnikuman about Terryman stopping a bullet train... from hitting a puppy. Wikia stated,

In the 21st Olympics, he (Terryman) made it to the third preliminary round, shoving bullet trains, but was disqualified for stopping his train from hitting a puppy (touching the train twice resulted in a disqualification)

Image source

Reference: ほかこ's Hatena Blog (Japanese)

The cross-dressing idol unit in episode 3 is certainly a parody of many idol units (as seen in the naming proposal): iM@S (maiM@S), PriPara's SoLaMi♡SMILE (KoMeMi☆SMILE), Aikatsu! (MaiKatsu), Love Live! (Love Rice), etc.