Yanda

Yanda (ヤンダ), actual surname Yasuda (安田), given name unknown, is a friend of Koiwai and Jumbo's, from the manga Yotsuba&!. He is a young man with blonde messy hair who is most often seen wearing a white shirt and tie, which appears to be his working clothes, though his occupation is unknown. Even though Yanda is mentioned in the first chapter, he does not appear until chapter 30. Jumbo calls Yanda "no good" for making lame excuses for not helping the Koiwais move. When he finally visits, he tries to get inside while Yotsuba is home alone, making her extremely suspicious of him. He is somewhat childish, as shown by the tit-for-tat pranks he plays on Yotsuba, including bribing her with candy then taking it back when it does not work, eating her ice cream, and prank-calling her. He also competes with Yotsuba to get to sit in the front seat of Jumbo's car, and likes to spend his money on things like soap-bubbles. Koiwai refers to him as his kōhai, but in what context he is Koiwai's junior is unknown. Yasuda is living from paycheck to paycheck, telling Koiwai that he eats instant ramen because he does not get paid until the end of the month. He never drinks alcohol, which Koiwai and Jumbo seem to find a bit unusual, though his reasons why not to have never been explained.

Koiwai
Koiwai is friends with Yanda, and often has him over at his house where Yanda eats instant ramen.

Yotsuba Koiwai
Yanda is considered Yotsuba's enemy, but he shows no sign of actually disliking her. His teasing is most likely just for fun. Yotsuba always has a negative attitude when she spends time with Yanda, and though Yanda initially seems to very much enjoy being a nuisance to Yotsuba, he later tries to be nicer. Whenever that happens, Yotsuba expresses surprise, but she still seems to see him as a rival.

Jumbo
Though Yanda, Koiwai and Jumbo are friends and hang out together, Jumbo seems to be less fond of Yanda than Koiwai is. For example, Jumbo calls Yanda "no good" for not helping Koiwai move and when the three of them go to the ranch together and Yanda says the cows aren't cute because they're so big Jumbo takes this as a personal insult, saying "why can't they be huge and cute?". He also encourages Yotsuba to "go beat" Yanda, when she tells him she is going to.

Asagi Ayase
Yanda was, like Jumbo, amazed at Asagi's looks the moment he saw her, and is attracted to her which triggers Jumbo's rivalry. Yanda has a girlfriend of his own, Miki-chan, but she has never been seen and Koiwai assumes that she has broken up with Yanda because she has not been answering his calls for months. That does not stop Yanda from trying to get somewhere with Asagi though, and when Jumbo tells him that Asagi has a boyfriend he replies "that doesn't matter", which amazes Jumbo.