The chocolate dipping sauce comes in tart cup that you can eat after you finish dipping your fries. An order of medium fries with the sauce sells for 340 yen (~$3.24 US).
The move seems a natural (if weird) extension of the sweet and savory pairings that have been popular of late and have seen such items chocolate-covered potato chips as well as numerous sweet potato fries (see here, here, and here for example).
The chocolate pie sports both a chocolate shell and a chocolate filling (it seems similar to a chocolate pie I tried at McDonald's in Hong Kong). The shake seems like your run-of-the-mill milk chocolate shake.
Ghana is a brand of chocolate made by Lotteria's parent company, Lotte.
The limited-time items are available starting tomorrow, January 9 and will be available through mid-February while supplies last (i.e. through Valentine's Day).