I had to check.
As of now it looks like the Vita is actually selling worse than 2013 PSP (would be nice if someone can show this on a graph)
Vita Week 17,2017 YTD: 221.432
PSP Week 17, 2013 YTD: 241.904
The PSP was discontinued the following year (2014)
Vita - Week 18, 2012 - YTD 250.773 (you should be comparing to week 18 btw, since Famitsu is on Week 18).
Also this looks like the titles we're getting for the next couple of months in Japan:
Switch
05/12 - Minecraft: Switch Edition - Digital only (mentioning because it's Minecraft)
05/26 - Ultra Street Fighter II: The Final Challengers
06/01 - Seiken Densetsu Collection
06/16 - Arms
06/29 - LEGO City Undercover
07/20 - Cars 3: Shouri e no Michi
Fate/Extella: The Umbral Star (Limited Edition)
07/21 - Splatoon 2
3DS
05/11 - Attack on Titan: Shichi-Kara no Dasshutsu (Attack on Titan Visual Novel?)
06/01 - Ace Combat 3D: Cross Rumble+ (Welcome Price!!)
06/01 - Ridge Racer 3D (Welcome Price!!)
06/01 - Attack on Titan: Jinrui Saigo no Tsubasa CHAIN (Spike Chuns...
06/01 - Tales of the Abyss (Welcome Price!!)
06/22 - The Alliance Alive
06/29 - Radiant Historia: Perfect Chronology
07/13 - 100% Pascal Sensei: Kanpeki Paint Bombers
07/13 - Ever Oasis
07/13 - Hey! Pikmin
07/13 - New Nintendo 2DS XL (Black and Turquoise)
07/13 - The Snack World: TreJarers
07/20 - Farming Simulator 18: Pocket Nouen 4
07/20 - Layton's Mystery Journey: Katrielle to Daifugou no Inbou
07/29 - Dragon Quest XI: Sugi Sarishi Toki o Motomete
08/03 - Dai Gyakuten Saiban 1 & 2 Special Edition
08/03 - Dai Gyakuten Saiban 2: Naruhodou Ryuunosuke no Bouken
PS4 (not sure which ones are digital here tbh)
5/18 - Danganronpa 1-2 Reload
5/18 - Prey
5/18 - Titanfall 2 (EA Best Hits)
5/25 - Assassin's Creed Syndicate (Ubi the Best)
5/25 - Ginsei Shogi Aun Toushin Kongou Raizan
5/25 - Guilty Gear Xrd: Rev 2
5/25 - Summer Lesson: Miyamoto Hikari Collection
5/25 - Ys VIII: Lacrimosa of DANA
6/1 - FIFA 17 (EA Best Hits)
6/1 - Tales of Berseria (Welcome Price!!)
6/1 - Tekken 7
6/8 - The Sexy Brutale
6/20 - Final Fantasy XIV Online: Complete Pack
6/20 - Final Fantasy XIV: Guren no Liberator (Collector's Edition)
6/22 - God Wars: Toki o Koete
6/29 - Far Cry Primal (Ubi the Best)
6/29 - LEGO City Undercover
6/29 - Portal Knights
6/29 - Zettai Zetsubou Shoujo: Dangan-Ronpa - Another Episode
7/6 - Gundam Versus
7/6 - Omega Labyrinth Z
7/13 - Final Fantasy XII: The Zodiac Age
7/13 - Hakoniwa Company Works
7/13 - Hakuoki: Shinkai - Fuukaden
7/20 -Cars 3: Shouri e no Michi
7/20 - Iwaihime: Matsuri
7/20 - MXGP3: The Official Motocross Videogame
7/20 - Under Night In-Birth Exe:Late[st]
7/24 - DiRT 4
7/27 - Naruto Shippuden: Narutimate Storm Trilogy
7/29 - Dragon Quest XI: Sugi Sarishi Toki o Motomete
Vita
5/11 - Owaru Sekai to Birthday
5/18 - Danganronpa 1-2 Reload (Best Edition)
5/18 - Rewrite Harvest festa!
5/25 - Daredemo Shodan ni Nareru Igo Kyoushitsu
5/25 - Love of Ren'ai Koutei of LOVE! (Limited Edition)
5/25 - Marginal #4: Road to Galaxy (Limited Edition)
5/25 - San Goku Shi 13 with Power-Up Kit
5/30 - Ys Origin
6/1 - Shiin
6/1 - Tsukitomo. Tsukiuta 12 Memories
6/08 - Shiro to Kuro no Alice
6/22 - God Wars: Toki o Koete
6/22 - Tokyo Yamanote Boys for V: Main Disc (Special Edition)
6/29 - Karumaruka * Circle
6/29 - Osomatsu-san: The Game
6/29 - Tsumigui: Sen no Noroi, Sen no Inori for V
7/6 - Omega Labyrinth Z
7/20 - Farming Simulator 18: Pocket Nouen 4
7/20 - Iwaihime: Matsuri
7/20 - Under Night In-Birth Exe:Late[st]
7/20 - World Election
7/27 - Grisaia no Kajitsu - SIDE EPISODE -
7/27 - Hiiro no Kakera: Omoi Iro no Kioku
7/27 - Kenka Bancho Otome: Kanzenmuketsu no My Honey
7/27 - Utsusemi no Mawari
7/27 - Wagamama High Spec