It's about an orphaned high school boy and his toddler brother with a Jerk with a Heart of Gold old woman whose children has passed away. Also, the high school kid has a part-time job as a babysitter at the school's daycare, full really cute kids and babies, somewhat forced on him. This manga might as well be the trope codifier what with all the "aaawwww..." moments it has in every chapter! The entire manga is full of Sweet Dreams Fuel.
All the kids wind up worshiping Kamitani after he stops a cat from attacking a baby chick.
After that, Takuma starts copying everything Kamitani does. The reason is because he saw how amazed his little brother was at Kamitani's feats and wanted to be someone his twin could look up to.
At one point, during a trip to the mountains, Ryuuichi ends up befriending a child spirit of the mountain who has some sort of power to cause snowstorms, Ryuuichi gives him his gloves, which prompts the spirit to smile, stop the snow and place Ryuuichi near his friends again.
Kazuma and Takuma's father has trouble getting close to them at one point because of his acting career. Then it turns out that they really did care about him and know him; They watch his movies all the time! It's just that his mother had recently shown them a movie where he plays a kidnapper.
At one point, Kazuma gets sick and Takuma has to go to the daycare by himself, which causes him to latch on to Koutaro as a Replacement Goldfish. Although Taka is initially jealous, after he hears that Takuma is alone, he fofers for the three to play together.
Kotaro's insistence on staying with Ryuuichi when he's sick. The Chairwoman has to take him out of the room, so he immediately plasters himself to the door. They then work together trying to make a mixture of hot tea, honey, and lemon for Ryuuichi.
During the Beach Episode, Kotaro becomes a little bit afraid of the water, but he leaps right in when he sees his older brother get submerged.
While a number of chapters have alluded that Hebihara-sensei is not as cold-hearted as he seems, his softer side was fully culminated in chapter 64, where he convinced the runaway Taka to return home to his mother and brother, and fondly compares him to Shizuka, though not without giving him a stern lecture for causing so much trouble.