Yonro (よんろ) lives next door from Shin-chan's family at room 203. He attended Tokyo Kasukabe University, not Tokyo University as Misae had mistakenly believed. Misae and Hiro frequently invited him over to fancy dinners at their house being very supportive of him so that one day when Yonro goes into a successful political career, he would thank them with lots of money and gifts. When Misae and Hiroshi found out that he wasn't attending Tokyo University, they practically abandoned him. He has visited Shin's family when they moved back into their old house. He works at a supermarket as a part-time job.
Because of the name that his family give him, people who met him for the first time often think that he retake the entrance exam for four times even though its three before he really took the fourth. The amount of exam retake matches his name by coincident. Whenever he think about passing the entrance exam, he always get nervous and start to make mistakes or being clumsy. The first time he failed the exam is because he gets too nervous and end up not sleep during the night before the exam so he end up sleeping during the test. The second time he failed the exam is because that he gets too nervous that he mistook test area for horse race area and went to watch the race so he didn't take the exam. The third time he failed is because he gets to nervous and end up having diarrhea during his test.