After wittnessing his grandfather's demise, Kouji sits for first time on the Hover Pilder, the tiny aircraft must be connected to Mazinger's head to get the robot running. Feeling uncertain (because he does not know how piloting it) and frustrated (because his little brother is nagging him about it being NOT a good idea), Kouji presses a random button... and the Pilder's glass hatch lowers suddenly, almost cutting his head off!
Finally, Kouji manages landing the Pilder down on Mazinger and starting the robot. Then, Mazinger goes on a rampage because Kouji has absolutely NO idea of what he is doing. Mazinger emerges out of the lab, destroying what was left of Kouji's grandfather's manor, wastes the place, almost kills Shiro several times, and its rampage only ends up when Aphoridte shows up, holding the Mazinger's leg to prevent it from stomping Shiro. Then Mazinger kicks Aphrodite accidentally. A beautiful beginning for the prototypical Takahashi Couple.
Yuri, Sayaka's cousin. She was cranky, demanding, a tad proud, demanded all went her way and everybody paid attention to her and seemingly had a crush on Kouji. Kouji remarked she was DEFINITELY and UNMISTAKABLY Sayaka's cousin, much to the annoyance of his battle partner.
Episode 19. Boss. "Hi, all! I am celebrating my birthday. Everyone is invited, but you will have to pay up to assist. Take your tickets... Why is everybody running away?". The worst part is Kouji had to try and explain him why.
In episode 27, Ashura captures and scans Aphrodite A in order to learn to build a photong engine. The records are destroyed and Ashura is stricken, but Dr. Hell remains calm and states surely he/she can recall some detail of the scan. Then Ashura stammers since the computer was recording it, he/she did not commit anything to memory. Dr. Hell's tantrum was simply beautiful.
Episode 28: Kouji and Boss accidentally headbutting each other as playing soccer. They fall down and remained lying face up for a while, watching clouds and remarking it is a very peaceful day (and Kouji states he does not want thinking about Dr. Hell today. Cue Kikaiju attack).
Episode 29: Kouji sees a Kikaiju is approaching the town. He remembers Aphrodite had walked by shortly before, and he panics out thinking of Sayaka. He gets so freaked out he gets on a bike and rides away... without realizing it is not HIS bike. Seconds later the real owner shows up, yelling: "You thief! That is my bike!"
Later, Boss is in the Institute, panicking about Mazinger losing. One of scientist states off-handily: "Then all of us will die". Right then Boss sees the Kikaiju marching towards the Institute, and faints. Shortly after he wakes up, sees the Kikaiju and faints again.
Episode 30: Shiro is breeding carrier pigeons. After Kouji and Sayaka mock from him, telling he should keep up with the times, he got mad and stormed off. Shortly after Boss and his group suggested him paying his brother back by writing a letter full of insults and sending it to him by pigeon. Later the four of them were trapped inside a mine by a Mechanical Beast -Brutus M3-, and they sent a pigeon to Kouji to warn him. After waiting for a while, Shiro realized he had sent the insulting note, so he wrote another letter explaining the situation and begging his brother help with this one-liner: "In God, Buddha and kouji Kabuto we trust."
Episode 48 (Boss Borot's first appearance) is a CMOF from beginning to the end. Highlights include: Boss, Nuke and Mucha donning a very shabby, goofy-looking robes and toy guns to pretend they were a terrorist group, and kidnapping the three professors (Morimori, Sewashi and Nossori) to force them to build a Humongous Mecha using junk and scrap metal; Sayaka supporting the plan after learning about it because she thought both she and Boss could gang up on KOUJI; the Institute's lab assistants analyzing one of the "guns" left by the kidnappers several times because they did not believe it was exactly what it looked like -a toy-; Boss listing all weapons he wanted his Humongous Mecha was fitted with, as Morimori very patiently explained no one of them was possible due to the robot made with scraps (enough funny, it could be seen like a Super RobotDeconstruction. "No, it will not have a Rocket Punch because the material is very weak and the fist would shatter upon impact."); Boss trying to enter into the cockpit; Aphrodite A unwillingly dancing with Boss Borot cause Boss had no idea of how piloting it; Baron Ashura and Professor Yumi having IDENTICAL reactions when they saw Boss Borot for first time; and Kouji -of all people!- getting jealous not only because he had needed Sayaka and Boss to win the fight but also because Sayaka was -gleefully- rubbing salt on the wound by going out with Boss.
Count Brocken's body punching Count Brocken's Head. Also, Ashura's male and female sides arguing with themselves before coming to blows.
In one of the late chapters, Sayaka thinks Kouji is dead and she hugs his fallen body, crying and and telling she loved him. Then she realized he was just pretending being dead. Then she decided killing him for real.
In the Go Nagai episodes -and long after in Shin Mazinger - Boss, Mucha, and Nuke have since played soccer with Count Brocken's head. And it was glorious.
As said in an imageboard: Brocken ball! The game where everyone wins, except the ball. Which is Brocken.
In episode 54 Mazinger-Z has to ski down Mount Fuji. Oh, my insides...