New Game+ Guide:
As of Game Version 1.4 and later, a new New Game+ option is available. To unlock it, you need to have a game saved in the latest version of the game (you can load and resave old saves). Once you have this, when you go to start a new game, you will reach a new menu after answering the starting questions. From there, you can choose several options to improve your starting game.
The Carry-Over Menu
The list, in order, is: Strength (All Stats besides Wisdom), Wit (Wisdom Stat and Skill Points), Trusted Family, Naughty Sister, Money, Companion LV, and Indomitable Body.
The second to last choice is 'Redo', letting you reinput your choices, while the last one is the choice to not carry over points.
Point Total
You receive a pool of points based on the amount of your last autosave only. Each save has an individual score (only calculated once you save after ver 1.4), so to get the max score, you must achieve everything below on a single save. The game will only remember the latest score, so later autosaves can reduce your New Game+ point pool total if they have a lower score. If you have an old save from before 1.4, load the save and then resave it in any slot outside of slot 1 (the new autosave slot); the game will recognize any accomplishes in that save, even if you reached them before you load into 1.4.
You receive points as follows:
1 point each 10 days that have passed, up to a cap of 10 (55 days=5 points, 216 days=10 points)
2 points for a completed panty collection
2 points for completing the story
2 points for clearing the Great Adventure
2 points for clearing Yukari's favorability event
2 points for clearing the Food Menu challenge early on in-game
2 points for clearing the Seal Subjugation event in the alternate branch of the game
2 points each for reaching LV 5 favor with Kana, Yui, and Kasumi
1 point for defeating Great Squid (post-game subjugation)
1 point for defeating Psycho Macho (post-game subjugation)
1 point for defeating Menhera-chan (post-game subjugation)
1 point for defeating Silent Killer (post-game subjugation)
1 point for defeating Seal Heroes (post-game subjugation)
1 point for Super Adventure Cleared
2 points for finishing the Onsen Event
This caps at 30, even though you can reach 36.
Your points are then divided by 2, rounded down, before giving you your max total of...
Grand Total: 15 max points.
Point Allocation
You can put up to five points in all choices except Indomitable Body, which simply gives the ability once chosen.
Strength (強さ): Each point gives 30 to all stats but Wisdom.
Wit (賢さ): Each point gives 40 to Wisdom and 40 Skill Points.
Trusted Family (信頼できる家族): Each point gives 50 to Sister's Trust and 2 to Guild Reputation.
Naughty Sister (えっちな妹): Each point gives 50 to Sister's Interest and 20 to her Lust.
Money (所持金): Each point gives 10,000 in money.
Companion LV (仲間のLV): Each point raises Companion LV by 15 (120 power each for Kana, 90 power each for Yui, likely a retroactively boost for Kasumi as well)
Sturdy Body (不屈の肉体): Costs 2 points and gives the 'Healing' ability next to 'Cooking', +10 to max actions points, as well as the combat skills: Atk Up, Def Up, and Auto-Heal; can only be bought once.
Other Bonuses
Other bonuses include carrying over the pajamas unlocked in the latest autosave, as well as any unlocked sex positions from the latest autosave as well.
Hope this helps guide anyone wanting to start a New Game+.