Kaito, Bane of Nightmares

Kaito enters attacking the same player, planeswalker, or battle the returned creature was attacking. This is a rule specific to ninjutsu; in other cases, when a creature is put onto the battlefield attacking, that creature's controller chooses which player, planeswalker, or battle it's attacking.

As you activate Kaito's ninjutsu ability, you reveal Kaito from your hand and return the attacking creature. Kaito isn't put onto the battlefield until the ability resolves. If Kaito leaves your hand before then, he won't enter at all.

Kaito's fourth ability cares whether opponents lost life this turn, not how their life totals changed. For example, an opponent who gained 2 life and lost 1 life in the same turn still lost life that turn.

Kaito's second ability causes him to stop being a planeswalker during your turn as long as he has at least one loyalty counter on him. While he's a creature, damage dealt to him won't cause loyalty counters to be removed. You can still activate Kaito's loyalty abilities.

If an opponent lost life this turn and subsequently lost the game, Kaito's fourth ability still counts that player when determining how many cards to draw.

Although Kaito enters attacking when his ninjutsu ability resolves, he was never declared as an attacking creature (for purposes of abilities that trigger whenever a creature attacks, for example).