It seems that this is not the first episode, as we saw clips of them using the first episode of Shinkenger and this uses footage from Episode 3. Maybe it is the first and the 'origin' story will be told later.
"The Team Unites"
The five Rangers are training with Jii but Mike isn't doing well. The bad guys send a monster to increase the Sanzu river. Bulk shows his 'dojo' to his 'nephew' Spike inside a garage. Jayden plays with his lion zord and Jii tells him no one knows where Mike is. Mike with two friends, who ask where he has been, they say he was a good gamer. His not much with the information. The monster comes out of a crack and punches victims. Mike runs towards it. The monster Rofer attacks the friends. Mike morphs and tries fighting it. Some lame lines later... Mike falls from a building and Jayden arrives to fight the monster. The monster starts tot dry up and leaves.
Back at the Shiba house, they bandage up a shirtless Mike. Jayden tells him to stay away from his friends. Mike says he is going to go to check on them. At the video game arcade, he sees them and he narrates that he won't be able to hang out with them anymore. Mike practices at night at the same time that Jayden does. Rofer and the Moogers attack again. Four Rangers morph. Rofer comments on Green missing and he arrives and morph and they fight the Nighloks (which seems to be the name of the whole group of villains). Green takes the foe on his own, Jayden intervenes but Mike has tangled him up and bests him. Rofer becomes big. Mike makes his zord 'Bear Folding Zord' big and he changes into Mega Mode. He enters his cockpit and unfolds his saber (the new one) and puts it in place. The Bear fights the monster. The other Rangers make their zords big and change to mega mode. They form the Samurai Megazord. They stay still and focus on the monster and manage to defeat him. Back at Shiba House, they all applaud Mike. Mike says he couldn't do it without Jayden. They then put their hands together. Real sappy moment.
It is very much like the Shinkenger source, some fans may complain, but if the writing in Sentai is good, why not transfer the story? American kids can't see Sentai, so why not have it? But I do wince at the monster's goofy dialogue and rhyming. Also, the group are way too serious, they say Mike is the funny one but so far in this episode he is rather serious. One obvious line: "Mike, You have come a long way." I do like they kept most of the names from Shinkenger such as the Sanzu River, Dayu, and the Shiba House. The inclusion of Bulk is very welcomed and doesn't seem too wedged in. Trying to stay true to Shinkenger and also please Mighty Morphin fans and get them nostalgic on MMPR is a big task. I didn't think these two could mesh but in this episode, they mesh with ease.
Being a nitpicky fan, I am not fond of Power Rangers Samurai opening credit sequence. They are obviously paying homage to the first season with the cast member title cards. The song is fine but the font choice seems a bit lazy and the title cards for each castmember seem to go too fast and the rest of the sequence doesn't have the rhythm of past seasons. I do like how all the villains finally have a group name, it has always been just by the name of the main villain. From this one episode, you can't really can get a read on the characters. By the way, the close caption calls the background theme music as 'lively rock music' and the 'Samurai Strike' at the end they call as 'Samurai Slash.' For kids, things would have probably get very confusing. As they don't explain what their symbols represent and why they go into Mega mode. The villains do explain their plot.