From the manga habit:

Shiina is a serious man who has wanted to be a zoology professor since he was a child. He was infamous for always carrying around many massive books. Now 28 years old, Shiina is an associate professor who works diligently to train future zoologists at a university while looking after his childfood friend, Chitose. Chitose is also an associate professor in the biology department and apparently always walks around with penguins. So he is quite infamous in his own right. Chitose has a weak constitution and always needs Shiina’s help. This manga focuses on the trials, tribulations, and future of the young associate professor, Shiina.

To cut costs at the Kusunoki Apartment Building, the new landlord has been appointed from the owner's family. Third son, Yuuto, will now serve as the tenants' landlord and chef while attending...elementary school?? A wonderful, heartwarming short story about 3 seemingly dissimilar adult tenants who are all brought together by the determination of their lovable young landlord.