Frog in a Well (井の中の蛙, I no naka no kawazu) is the 578th chapter of the Gintama series. Umibouzu and Utsuro starts fighting as Umibouzu reflects upon a conversation made in the past.
A youthful Umibouzu was seen gazing at the galaxy of stars while having a conversation with a young Mutsu, who was put under his charge by her father, a close friend of his and the head of the space pirate Chidori.
Back in the present, Utsuro talks about his first impression on Umibouzu, believing that they will end up battling each other just like now. He also believes that he will be able to find the answer he seeks through Umibouzu, for they still cannot avoid wanting to prey on others despite already being the strongest. The Yato, who rejects the idea of him holding the strongest title, rebuked this: he couldn't care much about the world and would rather protect what's under him just like a frog in its well. Utsuro thinks otherwise, as he feels that Umibouzu is a stalwart fighter that can only be born once every several thousand years. However, the fighter is still going to die because Utsuro himself will destroy him; he then charges towards Umibouzu. At the other side of the battlefield, Mutsu senses something in the midst of fighting and freezes in her tracks.
The young Mutsu inquires whether if Umibouzu has ever met someone stronger if he doesn't consider himself the strongest in the vast universe. The latter replies that as a hunter he wasn't able to measure the strength of his opponents, because there is no room for comparison in the first place due to their differences. Mutsu then reveals the reason for Umibouzu's title as the Yato hero: the Yatos' home planet Kouan was destroyed together with many Yatos under a merciless attack from the League of Planets. This caused the Altana to gush out from underneath the devastated planet and as a result, creatures with strange mutation appeared. Amongst them was a parasite known as Orochi, who rendered the planet inhabitable as it made the Altana its nest by devouring it, attacking anything that gets close. It was Umibouzu who singlehandedly reclaimed back Kouan by destroying the parasite.
Umibouzu disagrees, as he went Kouan simply because he lost a bet with his drinking pal, and had to pick up ladies back in the abandoned hometown as a punishment. He wasn't there to do something heroic, though he did ended up fighting some fellow over there. As the scene cuts back to the present battle, Umibouzu had a deja vu moment - something "stood up".
Back in his flashbacks, a confused young Mutsu didn't get what he meant by "stood up", and the man explains that it's an adult instinct. He immediately wanted to settle down and have children the moment he met that fellow. He wasn't able to shake off the feeling no matter how hard he tried. As the scene cuts back to the present, Umibouzu was overwhelmed by Utsuro due to him getting distracted, and he was sent flying with the latter's punch. He proceeds to crush his own testicles in attempt to stay focus and, driven by his overpowering desires to protect his children, sends a punch straight at an incoming Utsuro. Utsuro's upper right arm was ripped off together with his sword from the punch.
The young Mutsu was astonished at Umibouzu's actions to suppress his instincts, to which the latter was thankful to as by doing so he was then able to focus on the fellow, a woman. This greatly confuses Mutsu, as she thought that Umibouzu was talking about Orochi. The latter then reminded her that he was there to pick up ladies; he need not have to go to great lengths for a mere parasite. Back in the present, Umibouzu notices that Utsuro's arm is regenerating, and notes that he has the same Altana as that woman.
As both the young Mutsu and the present Utsuro inquire on her identity, it was revealed that the woman is Umibouzu's wife.
- Umibouzu: (To Utsuro) Get lost. I don't need the title of the strongest. And I couldn't care less about what happens to the world. Call me a frog if you want, but I'll die to protect the bottom of my well. I'm fine with being just a frog.
Characters in order of appearance