Christmas Cake: A rare male example at the very beginning. He's 25 years old, does quite well for himself at his job and is seen as attractive by most women, but he's still a virgin and terrified of remaining one. Luckily, he meets Yura not long after.
Genius Ditz: He's actually quite competent at his job and is something of a rising star in the office. When it comes to everyday affairs, particularly romantic ones, he's completely clueless.
Happily Married: To Yura. Maintaining a stable marriage is the focus of the story.
Idiot Hero: Far from the sharpest tool in the shed, almost always thinking about sex, and often fails to consider Yura's feelings. Still a good guy, though.
The Loins Sleep Tonight: You just can't win 'em all, Makoto. (Actually, he can't win most of 'em, because when he can get it up, more often than not he can't last a full minute. This continues past their first wedding anniversary.)
Man Child: Despite being 25 at the beginning of the series he still clearly acts like he thinks he's still in high school.
Nice Guy: He's thickheaded, but he tries his best to be a good husband and friend.
Hurricane of Euphemisms: Frequent target of this (usually from Rika), being inexperienced with sex and fairly innocent.
My Girl Is Not a Slut: She grow up with this mentality, unlike her far more loosed up sister and after getting married, she had inicial troubles dealing with her new discovered sex drive. She gets better.
I Want Grandkids: Whenever she gets in contact with Yura, she'll always drop the hit that there's still no babies in her marriage, and would blame Makoto's bed skill. She even asked Kyouko to get in the picture so she could make sure they have babies.
Let Her Grow Up, Dear: While her husband was in shock on Jun's love life and was all about "Girls must remain maidens until marriage", she was more interested in how was her affairs and even points how she wasn't a virgin neither when she married him.
Obnoxious In-Laws: Downplayed. She mostly is obnoxious when there's hints of a possible pregnacy and in other cases, she's obnoxious to her own son because she wants him to improve.
Makoto's big brother.
Big Brother Bully: Played for Laughs. He genuinely wants to help, but keeps butting incessantly in Makoto and Yura's sex life to give them "advice" that they don't even really want in the first place.
A-Cup Angst: She's even smaller than Jun, who's still developing, and her husband's attitude that Buxom Is Better just makes it worst.
Cool Big Sis: She's a better sex mentor to Yura than her husband is to his brother.
Tsundere: She may love her husband but always has to hold him back everything he's admiring Yura's...and Rika's, and even Jun's beauty.
Makoto's little sister.
First Guy Wins: After having some adventures mentioned below, finally makes an emotional connection with an e-mail pal. It turns out to be her first love, Inoue.
Horrible Judge of Character: in her search for true love, she manages to a) have a one-night-stand with a man she practically just met (who — shock! — turns out to have a girlfriend), right after breaking up with her boyfriend because she feels their relationship has lost the spark, b) become the (oblivious) fifth sex-friend of an obvious playboy (despite the warnings of her best friend, she is devastated upon seeing him enter a love hotel with another girl) and c) pursue an affair with a homely middle-aged married man, this time mere hours after first talking to him. One can almost not blame her father for calling for a family conference about her behavior...
It Must Be Mine: The reason why she only sleeps with married men is because she's the type of person that wants what other peoples have. That's her whole deal with wanting Makoto to cheat on Yura with her.
Daddy's Girl: After her parents got divorced, she stayed with her father and this definitely formed her. When her mother comes to offer her to leave her father and move in with her, Rui decides to stay with her father and finally fully accepting Kayo as his lover and her (future) Stepmother.
Pervert Dad: Has a habit of peeking on his daughter in improper situations, due to sexual frustration.
All Women Are Lustful: Turns out she absolutely loves sex and is not above experimenting with things, including bondage.
Happily Married: Her second marriage, to Rui's father Hisao, is very happy compared to her first one.
Noodle Incident: For a long time, she frequently compared things to her previous marriage, then begins muttering to herself how this may have or may have not been a reason why her marriage failed... without ever really mentioning what exactly she means, leaving people wondering.
Bastard Boyfriend: He's only interested in Rika when he wants sex and cheats on her multiple times. Not that Rika is any better.