In a classroom at the ARC Academy Japanese language school near JR Shinjuku Station in Tokyo, Hiroshi Oba held up drawings of a piano and a guitar to a group of about a dozen young people.
"Watashi wa piano ga toku ni suki desu," he used as an example sentence, which means, "I particularly like the piano."
Oba, 58, was teaching the class how to use "toku ni," or "particularly." He has been teaching only for eight months, but appears to have learned a few tricks of the trade.
His students are from all over the world - China, Thailand, France, Russia, Italy and the United States.
"Thank you, teacher. That was fun." Listening to the students chat with him in halting Japanese after class brought a smile to his face.
Oba originally worked in science-related fields. After graduating from university, he worked at a Tokyo trading company that specialised in electronic devices.
In 1995, he and some partners started a company that dealt in products such as televisions for hotel rooms. As one of the firm's directors, Oba travelled frequently within Japan and overseas to help open sales routes and develop new products.
Looking for a new field, in 2011 Oba found a job at a food company near his home, where he worked until early last year. During that time, his two eldest daughters left home due to work and marriage. The remaining daughter went to the United States to study in the summer of 2012.
Oba and his wife found themselves in their now-lonely living room, talking about what to do with the rest of their lives, with exchanges such as "Which of us will die last?"
"I didn't want to just die and be known as that old guy who was a good salesman," he said.
Oba remembered his youngest daughter hitting the books constantly to achieve her dream of studying abroad.
"I want to study for some kind of certification," he told his wife. She thought about it and said, "Maybe I'll do something, too."
He looked into what certificates were within reach, and becoming a Japanese teacher caught his eye. He liked talking with young people and thought his experience as a corporate executive could be useful.
His wife opted for a different national-level certification and together they got to work.
Hitting the books
Oba entered a training course run by ARC Academy in January 2013.
He had not studied anything at a desk since his university days, so things were difficult at first. He said it took him a week to plan a 15-minute mock lesson.
It was difficult, but he became inspired when he saw his wife hard at work at her desk in the next room.
After a year, both Oba and his wife passed their respective tests.
At 57 years old, he was hired by the academy and in April began working as a non-regular instructor teaching foreign students who hope to enter universities or technical schools.
These students are on limited visas so are highly motivated.
For the twice-a-week classes, Oba creates drawings and other teaching materials to help his students quickly learn practical conversation skills.
"I'd be so happy if a student came to me and said, 'Teacher, I got in,'" he said.
With his direct gaze and serious expression, Oba certainly looks the part of a teacher.
60 per cent volunteer to teach
There is no national certification to become a Japanese language instructor, but most schools in Japan require some kind of knowledge or experience to teach foreign students.
A person is generally considered qualified to teach if he or she has majored in Japanese language education at university, attended at least 420 hours of classes at a private training course, or passed the Japanese Language Teaching Competency Test run by the Japan Educational Exchanges and Services association.
There are 156,843 people studying Japanese nationwide, according to a fiscal 2013 survey by the Cultural Affairs Agency.
The number of Japanese language schools has been increasing, and there are 31,174 people working as Japanese instructors. Nearly 60 per cent of them are volunteers.