Plain-Form CLAUSE + (そう/だ) as “heard that ___”
This grammar construct is used to express information that the speaker acquired from another source by hearing (or even reading) about it. This construct contrasts with the (Pre-ます-Form VERB/Stem-Form ADJ/NOUN) + そうです that conversely means “it looks/seems like ___.” The phrase Xによると, which translates to “according to X,” can often be seen accompanying this grammar construct to provide the respective source of information. While in the English language, the phrase “I heard that” can somewhat imply baseless hearsay or rumor, this connotation is not present in this Japanese form.
For verbs, any Plain-Form conjugation can be used. For い-Adjectives, the い-Adjective itself is used. For な-Adjectives and Nouns, the words themselves are used immediately followed with the respective (plain) conjugation of です。
T.V. no news no tenki yohou ni yoru to kyou ame ga furu sou da.
(According to the weather broadcast on the television news, I heard that it’s going to rain today.)
Sakuya, George Washington wa taiho sareta sou desu.
(I heard that George Washington was arrested last night.)
Kono recipe wa sugoku oishii sou desu.
(I hear this recipe is really delicious.)
Sono party wa tanoshikunakatta sou da.
(I heard that party wasn’t that fun.)
Atarashii tenkousei wa yumei da sou desu.
(I heard that the new transfer student is pretty famous.)
Kare wa captain na no ni, tenis ga jyouzu jyanai sou desu.
(I heard that he’s not that good at tennis even though he’s the captain.)
Kare wa pro datta sou desu.
(I heard that he was a pro.)
Kare wa hontou no sensei de ha nai sou desu.
(I hear that he’s not even a real teacher.)