Shiina-kun no Torikemo Hyakka

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.