When Shinjiro Torii first started Suntory Whisky, he hired Masataka Taketsuru to be his master distiller. Taketsuru left early on to form his own company, which eventually became Nikka. The brand carries a few varieties, but the ones you should start with are the Coffey ones.
No, it has nothing to do with coffee -- Coffey refers to the type of still used, named for its creator, an Irishman with the action-hero name of Aeneas Coffey. Coffey stills are a particular type of column still, as opposed to a pot still, the type used to make single malt scotch; importantly, they allow for continuous distillation, rather than in batches. The Coffey Grain is almost like an Irish whiskey, blending multiple barrel types.
While Coffey stills are generally used for grain whiskies, the Nikka also uses it to produce an all malt. It’s 100% malt and all distilled at a single space, much like a single malt scotch. However, not being distilled with a pot still disqualifies it from being classified as a single malt. This is probably for the best, as you shouldn’t expect it to taste like a Scottish single malt. Like the Coffey Grain, the Malt is beautifully sweet, but not at all cloying. It’s generally the same price as the Grain.