Naruto D20 - Vesuvian Isles
Tatsu fought during the 30 years war and barely survived. He is a pretty average ninja, he only ever reached the rank of chuunin, but he is widely liked and very good with children. It was a combination of these character traits that led him to being hired as the Acadamy Teacher.
Tatsu is a very strict teacher, but is still very likable. He is funny, but manages to remind his pupils that what they learn from him could one day save themselves, or someone they care about.
He is known for being a forgiving person, but his punishments can oftentimes be very strict. However, his punishments usually also suffice as teaching or training tools such as running laps, holding heavy things up for a long time, writing and rewriting text from a shinobi encyclopedia, etc etc. The punishment usually suits whatever he views the student as being deficient in.
Tatsu has a wonderful wife he met after the war and together they have one child, who the have agreed to not raise as a ninja.