This symbolism man.
Kenta falls in love with some mysterious girl name Seira. To make things interesting turns out that she is working for Tube as their Symbiotic Beasts whose job is to produce food for one of their Ground Beasts. Because of her meeting with Kenta, she starts to think twice about humans.
This episode pretty much feels like what will happen if Takeru will eventually learn the truth about Mio's past and her relationship with Tube. It kinda feels like they are experimenting on that element of acceptance once they decided that it is time for Takeru to learn the truth about Mio. For their first try, they did a really great job with it. I can feel the struggle that Seira is facing and cause me to pity her fate that she is tied in fate that she can't escape, making her one tragic character.
As for Kenta in this episode, I find his sudden interest in Seira a bit weird considering that in one episode, he had a love interest but decided not to pursue her now because of his mission as a Maskman. It feels like he is a being out of character when he fell in love with Seira in first sight. Even if that's the case, I kinda ignored it because of the episode's drama. The drama portions of this episode are the best parts of the episode that I forgot that this is a superhero show until they show us some fight scenes.
The drama of this episode deals with living a very short life and making the most out of it or the option of living a longer life, only to live long enough to be miserable. Seeing Kenta's reaction that Seira basically throw her "life" away just to save the life of a dying bird is really well done. The music and the way they shot his reaction made it really great. Same goes with the scene wherein Kenta learns the truth about Seira that she is working for Tube. For the tragic bit in this episode, it feels too cliché and too predictable, especially the part on how Seira died. I mean seriously, why do a freakin' slow motion?!
After Seira died, the scene is then followed with the standard "I will not forgive you, Tube!” the fight scene ensues, MOTW is defeated and the giant battle. Nothing much to talk about except that Great Five is back. Oh well, at least they didn't forget that Great Five still exists and is treated as Galaxy Robo's equal rather than given the treatment as the weaker first team mecha like how most Super Sentai mechas do these days. At the end, Kenta silently mourns about Seira's death and is later comforted by his friends.