Asama was the lead ship of a class of armored cruisers of the IJN, built in Britain in 1890's. She served in WWI, and later as a training ship until she was scrapped after WWII. Her main armament consisted of four 8-inch cannons in two twin gun turrets, along with a total of 34 secondary guns of various calibers. She was also fitted with five torpedo tubes (not included in game for balancing reasons).
In game, Asama is the first IJN heavy cruiser available, and is researched from DD Akizuki. One will find having to learn a significantly different play style from the fast and nimble destroyers, but despite her lumbering and obsolete appearance, Asama is a formidable cruiser and a good teacher to the ropes of what driving a CA is all about. It cannot perform guerrilla warfare of the later CAs due to lacking scout planes and AA-capable secondaries, but is a good platform to learn fighting off smaller ship classes, escorting friendly capitals, and staying alive and out of the harm's way.
Stick close to your capitals - pick a battleship and stay close to him, using your fast-firing and accurate secondaries in gradual fire mode to rain shells on DDs and CLs trying to approach. Your main guns have a decent punch, but reload slowly, so keep your secondaries handy and only switch to the big guns when they are ready to fire. Remember to converge them by pressing E right before firing, to ensure a tight spread, and immediately switch back to secondaries while they reload. Both your main guns and secondaries pack HE and AP shells, which means that you are very vulnerable to planes, and cannot take down enemy recon unless they are dumb enough to fly into your AAW. It is recommended to equip a piece of bulge armor to protect yourself from torpedo bombers, as well as DDs and subs. Remember that torpedoes have a minimum arming distance - sometimes it is possible to entirely negate an incoming torpedo attack by simply slowing down to a halt, and cackling at the enemy torpedoes clunking uselessly against your hull. Dive bombers can be a nuisance, but some smart maneuvering will often allow you to dodge at least most of the bombs. When the bombers "lock" onto a point in front of your ship to begin their diving run, hit the speed boost, and turn hard in either direction - you'll be surprised to find how often this will save you from serious damage.
Upgrades increase the rate of fire of your main and secondary guns, increase ship defence level, and sight range - all of which are very useful and worth unlocking.