Joyfull is a family restaurant chain throughout Japan. It is cheap but reliable, easy to order (even for foreigners), picture menus (sometimes translated into English), and a variety of Japanese-western dishes.
I kinda like it every now and then, even though it is not fine dining or particularly exciting food. Sometimes hitting up the Japanese family chain restaurant is the easiest while travelling somewhere new; sometimes you just need a break from adventure and want something reliable and familiar.
I realize if you are traveling in Japan perhaps these types of restaurants are different and strange compared to most American restaurants; maybe you have never tried the ubiquitous “hamburg” ハンバーグ (different than a hamburger ハンバーガー) that adorns the menus at this type of restaurant. These restaurants are actually a bit interesting to visit as a foreigner, so just because it is a chain, do not necessarily turn it down and give it a try if you have time. Also as a bonus, they are usually 24 hour, which often helps out a traveller who is not all the way time-adjusted, needs a hot meal and a place to sit down for awhile. Keep an eye out for its yellow sign with “Joyfull” in red text
Hint, try to pick up a “drink ticket” coupon before you go– it gives a decent discount on the soft drinks bar. Sometimes magazine coupon books will have them, or if you know someone who has been to Joyfull, the staff gives out the discount tickets (I think it is usually for ~every 500 yen spent) after the bill is paid to encourage people to return another time.